ELLISON, Judge.

 The appellant was convicted of manslaughter and his punishment assessed at a fine of $400 and 6 months in the county jail, for the killing of Daniel I. Gross in Fredericktown in August, 1934.  The cause was tried in St. Francois county on change of venue from Madison county.  The deceased was a hemophiliac, or "bleeder."   The appellant struck him on the jaw once with his fist.  A slight laceration on the inside of the mouth resulted which produced a hemorrhage lasting ten days and ending in death.  The State's evidence showed the appellant's assault upon the deceased was unprovoked.  The evidence for the appellant was that he acted in self-defense;  and his theory further was that Gross' death was not caused by the blow struck, but by his disease, aforesaid, and the failure to treat it properly. . . . [p. 970] . . . .

 For the State two eyewitnesses testified.  One of these was Mr. E. D. Anthony, city attorney of Fredericktown, a man 78 years old.  By him it was shown that the deceased was standing at the outer edge of the recessed entrance to his book and magazine shop in Fredericktown a little before noon on August 31, 1934, when the appellant from a point further west rapidly crossed the street diagonally to the other side and thence, after a very short interval, returned at a brisk pace, walking straight up to where the deceased was standing and with his right hand hit him on the left side of the jaw.  At that time the witness was about 20 feet away on the adjacent sidewalk.  The deceased retreated into his store, the appellant following and striking at him.  The deceased said, "Don't hit my face, you hurt me."   By that time the witness was passing in front of the door within 6 or 8 feet of the two men.  The deceased grabbed a book from the table and said, "Get out of here--get out."  The appellant turned around and went out.  During the whole time the appellant did not say a word so far as the witness heard.

 The other eyewitness was Mr. E. H. Bess, hardware and furniture merchant for 30 years in Fredericktown.  He was walking on the other side of the street, which was 50 feet wide, about opposite the deceased's store.  Glancing up, he saw the appellant walk real fast toward the deceased, who was standing at the edge of the entrance to his shop, and hit him with his fist on the left side of the jaw, and then turn away and walk down the street.  The deceased staggered back into the building and did not hit the appellant.  The witness did not hear either of them say a word, and only one blow was struck.

 For the defense two young women who were eyewitnesses referred to the occurrence as a "fight."  They testified the appellant and the deceased were scuffling on the sidewalk in front of the shop;  that the appellant started to leave and the deceased followed him four or five steps and hit him on the head with a book, whereupon the appellant struck the deceased and walked away.  The two girls were on the same sidewalk about 100 feet west of the shop when they first observed the difficulty.  They did not see Mr. Anthony, the State's witness, who would have been between them and the struggle if all were positioned as they testified.  Mr. Anthony on rebuttal declared the two girls were not anywhere in sight on that side of the street at the time.

 The appellant swore he did cross the street diagonally as Mr. Anthony testified, and that the deceased, who was standing in the doorway of his shop, called out and cursed him.  Appellant thereupon came back and walked up to the deceased, asking what was the matter.  The deceased assaulted him.  Appellant warded off the blows and pushed the deceased back.  The deceased took off his glasses, renewed [p. 971] the attack, and then, uttering foul epithets, retreated into the store and got a book.  Appellant started away, the deceased followed and hit him with the book, and appellant hit the deceased an ordinary blow in self-defense.  He swore he did not know the deceased was a hemophiliac.

 Regarding the evidence showing the physical condition of the deceased and the effect upon him of the blow struck by the appellant:  He was 36 years old and had been afflicted with hemophilia since birth.  He had been under treatment for that disease about 2 years before when he bumped his knee on a table, and was in the Veterans' Hospital in St. Louis for a short time.  He was below the average in height and overweight, or fat, as some of the witnesses said, and rather pale or anemic.  He walked with a slow draggy or hobbling gait.

 The two young women aforesaid who were called as witnesses by the appellant testified that after the difficulty had ended they walked on by the shop and saw the deceased standing in the doorway spitting out a little blood. R. O. Buzbee, deputy sheriff, said he had occasion about noon that day to go to the deceased's shop, and found him standing inside the door.  He was bleeding from the mouth and his jaw was puffed up and discolored.  Mrs. F. T. Gross, mother of the deceased, said she saw him that night about 6 o'clock.  His face, jaw, and lips were swollen.  His lip was in very bad condition.  He went to bed about 8:30 or 9 o'clock that night, but remained in bed only overnight, taking care of himself.  He was confined to his bed in his last sickness from September 5, 5 days later, and died on september 10.  One of the defendant's witnesses testified to seeing him at a picnic in Fredericktown on Labor Day, which was September 3.  He was standing by one of the booths.

 Dr. W. H. Barron, a physician at Fredericktown of 30 years' practice, treated him in his last illness.  He had known him for 15 years and intimately for 6 or 8 years, having been his physician on the occasion of his illness 2 years before.  The deceased came to his office in the morning of September 1.  His left jaw was badly swollen.  An examination disclosed that he had an abrasion or laceration on the inside of his lip.  It was an opening in the mucous membrane about one-eighth inch deep, but did not cut into the muscular tissue. The wound was bleeding slowly but not excessively.  His face was swollen and rather pale.  the doctor did not treat him on this occasion.

 Three or four days later the mother of the deceased called at the doctor's office and the latter prescribed treatment for him which included rest in bed, quietude, light foods, cold packs on the face, and a drug called ergot.  The doctor did not see the patient on this occasion.  Several days later on September 8 Dr. Barron was called [p. 972] to see the deceased in the latter's home.  The swollen condition of his jaw was about the same and he was pale and weak.  Lots of blood was coming from the mouth and also from the intestines and kidneys.  He was expectorating clots of blood coming from the abrasion in his lip.  Part of this blood was swallowed and going into the intestinal tract. The patient was vomiting some.  On September 10 the doctor was called to the deceased's bedside again.  The pallor in his face was more marked and he was going into a state of coma.  The pulse at the wrist was barely perceptible.  He could not expectorate and the blood from the wound was going into his throat. He died in half an hour.

 Dr. Barron gave it as his professional opinion that the death of Gross was caused by hemorrhage from the laceration in his mouth, the latter appearing to be the result of some sort of violence.  He described hemophilia an an hereditary condition of the blood such as prevents coagulation thereof and thereby permits hemorrhages to continue unchecked.  He further said these hemorrhages could occur spontaneously, without violence, but were usually more aggravated when resulting from trauma.  It was his opinion that the injury to the left jaw of the deceased would not have caused him to bleed to death if he had not been a hemophiliac.  He said the disease was incurable but that there were   treatments for it.  The treatments he prescribed were recognized, he said.  On crossexamination he was asked if eminent medical authorities did not advise blood transfusions for hempohilia, and was shown one recent text on the subject.  The witness answered that medical opinion on that question was not settled, and that he considered a transfusion ill-advised, in view of the patient's condition and envirinmnent when he saw him on September 8.

 He was asked if he didn't find the patient was bleeding rather freely from the kidneys on September 8 and 10, and he answered that he didn't see that, but understood it from the history of the case given to him.  He found no evidence of any violence to the body in the region of the kidneys or in the intestinal region, but said that some of the blood from the patient's mouth trickled down into the intestinal tract.  He was then asked his opinion as to whether the hemorrhage that caused the death of Gross was from the intestines, the kidneys, or the mouth, and he answered it was the continuous hemorrhage that caused the death, but that he didn't know whether it was from the intestinal regions, the kidneys, or the mouth.  On redirect examination he said large quantities of blood swallowed by an individual would go through the alimentary canal and intestinal tract and be thrown off by the normal action of the latter, and the mere fact that a person might pass blood wouldn't be an indication of bleeding at the kidneys.  But he repeated on recross and redirect [p. 973] examination that without making a test he couldn't determine where the blood came from; and that he made no such tests and found no symptoms indicating a hemorrhage of the kidneys except from the case history.  Other facts will be noted as necessary in the course of the opinion.

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 II. Appellant complains further that the proof was insufficient to support the verdict against him because all the evidence showed:  (1) That he struck in self-defense;  (2) and that the death of Gross was caused solely by the disease of hemophilia, and not by the blow struck.  Appellant is entirely wrong in saying all the evidence shows he acted in self-defense.  The testimony of two eyewitnesses, Messrs.  Anthony and Bess, was that he walked rapidly up to Gross and hit him before a word had been spoken or a demonstration made by Gross.  But it is true the undisputed evidence establishes that appellant struck only a single, moderate blow with his fist against Gross' jaw, which wa snot calculated to produce death or great bodily harm.

 Dr. Barron, the attending physician, gave it as his professional opinion that the death of Gross was caused by hemorrhage from the laceration in his mouth, and the evidence is clear that the laceration was produced by the blow struck by appellant.  But it was the doctor's furtheropinion that the blow on the jaw would not have caused the deceased to bleed to death if he had not been a hemophiliac.  He also testifed the hemorrhages from hemophilia might occur spontaneously, and admitted that he had learned the patient was bleeding rather freely from the kidneys, and, it seems, also through the intestinal tract, during the last 3 days of his sickness.  He made no examination of these parts, and the foregoing information came to him only as it was communicated with the case history.  He found no evidence of violence in the region of these organs, and stated blood from the wound in the mouth when swallowed might find its way into the intestines.  He also said the mere fact that a person might pass blood wouldn't be an indication of bleeding at the kidneys.  And yet the record shows that, when asked on cross-examination whether the hemorrhage that caused Gross' death was from the intestines, the kidneys, or the mouth, he said he didn't know;  and he also said that without making tests he couldn't determine where the blood came from.

 This somewhat equivocal testimony from Dr. Barron seems to leave the way open for a possible inference that hemorrhages starting [p. 976] spontaneously in the kidneys and intestinal tract, and being wholly independent of the hemorrhage from the laceration in the mouth of the deceased, may have caused his death. But, on the other hand, the doctor affirmatively expressed the opinion as a physician that Gross' death was caused by the hemorrhage from the laceration in his mouth (which, in turn, was caused by the blow he received), and he further said the passage of blood through the organs of elimination might occur because the blood had been swallowed.  It is therefore clear there is no foundation for appellant's contention that all the evidence showed Gross' death was caused solely by hemophilia.  And for the reasons just stated we are further of the opinion that the doctior's testimony was not so equivocal as to be self-destructive and make it impossible for a jury to find whether the deceased died from the hemorrhage in his mouth or from a different hemorrhage independently starting in his kidneys and intestinal.  The more natural construction of what he said, it seems to us, is that, while he could not be sure without making certain tests which he did not make, yet his professional opinion was that Gross' death resulted from the hemorrhage in his mouth.  His opinion as an expert on the question was competent and substantial evidence, and absolute certainty was not required of him.  29 C.J.s 640, P. 544, § 735, P. 640;  § 758, P. 644;  Kimmie v. Terminal R. Ass'n, 334 Mo. 596, 603, 66 S.W.(2d) 561, 564;  Gillick v. Fruin-Colnon Const. Co., 334 Mo. 135, 141, 65 S.W.(2d) 927, 930.

 Remembering the appellant was convicted of manslaughter, two questions remain:  (1) Was it an adequate defense that the appellant did not know the deceased was a hemophiliac, and struck only one moderate blow with his first, which ordinarily would not have been dangerous to life?  (2) Is he to be excused because the blow producing the hemorrhage would not have resulted fatally if deceased had not been a hemophiliac?  Both these questions must be answered in the negative.  Section 3988, R.S.Mo.1929, Mo.St.Ann. §  3988, p. 2793, provides that "every killing of a human being by the act, procurement or culpable negligence of another, not herein declared to be murder or excusable or justifiable homicide, shall be deemed manslaughter."  If one commits an unlawful assault and battery upon another without malice and death results, the assailant is guilty of manslaughter, although death was not intended and the assault was not of a character likely to result fatally.  29 C. J. § 137, P. 1150;  13 R.C.L. § 89, P. 784;  State v. Recke, 311 Mo. 581, 595, 278 S.W. 995, 998.

 Neither is it an excuse that appellant did not know the deceased was a hemophiliac, and that death would not have resulted but for that affliction. On this point 13 R.C.L. § 55, p. 750, says:  "The law declares that one who inflicts an injury on another [p. 977] and thereby accelerates his death shall be held criminally responsible therefor, although death would not have resulted from the injury but for the diseased or wounded condition of the person so injured."  And the doctrine is more fully set out in 29 C.J. § 57, p. 1082, as follows:  "If the deceased was in feeble health and died from the combined effects of the injury and of his disease, or if the injury accelerated the death from the disease, he who inflicted the injury is liable, although the injury alone would not have been fatal.  The same rule applies, although the disease itself would probably have been fatal, if the injury accelerated death.  It is immaterial that defendant did not know that the deceased was in the feeble condition which facilitated the killing, or that he did not reasonably anticipate that his act would cause death."  See, also, 51 L. R.A.(N.S.) 877, note;  Ann.Cas.1916C, 693, note;  16 Ann.Cas. 578, note; 4 Ann.Cas. 958, note.

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 The final assignment in the motion for new trial is that "the court erred in refusing to properly instruct the jury on excusable [p. 979] homicide, which was requested by defendant."  The record does show that such request was made.  In instruction No. 2 the court gave the following definition: " 'Excusable homicide,' as used in these instructions, means the accidental killing of another."  Section 3986, R.S.Mo. 1929, Mo.St.Ann. § 3986, p. 2792, provides:
"Homicide shall be deemed excusable when committed by accident or misfortune, in either of the following cases:  First, in   lawfully correcting a child, apprentice or servant, or in doing any other lawful act by lawful meands, with usual and ordinary caution, and without unlawful intent;  or second, in heat of passion, upon any sudden or sufficient provocation, or upon sudden combat, without any undue advantage being taken, and without any dangerous weapon being used, and not done in a cruel and unusual manner."

 It will be seen the section makes a homicide excusable when it is committed by accident or misfortune in instances specifically enumerated.  The instruction as given leaves out all these limitations, and simply tells the jury that excusable homicide means an accidental killing.  It was therefore more favorable to the defendant than he was entitled to, State v. Ryland, 324 Mo. 714, 720, 25 S.W.(2d) 109, 112.

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 Finding no reversible error, the judgment and sentence below are affirmed.

 All concur.