PHYSIOLOGY. 



C29 



enced physiologically by tin- fact of tin- closure of 

 the brain in n linn, unyielding case. The opening 

 of the cranium likewise does not alter the supply. 



The conditions under which the germicidal 

 properties of Ihe b|<>od ure at their highest have 

 IM-, n investigated liy l)r. von Kodor. The first 

 >f researches had reference to the compo- 

 sition of the Mood, mid proved that arterial blood 

 has a more destructive action on the 1 met criti than 

 venous, and that fresh Mood has a more power- 

 ful action than that which has Ix-cn shed forsome 

 time. Again, the germicidal power of the blood 

 was weakened in an atmosphere consisting en- 

 tirely of oxygen or carbonic acid ; on the other 

 hand, the removal of gases from the Mood had 

 no appreciable influence. The blood of rabbits 

 which had been poisoned by carbonic-acid gas was 

 not fatal to the bacteria. No difference in effect 

 was observed when the blood was kept in motion. 

 The germicidal power of the blood increased with 

 the temperature till it reached its. maximum at 

 from 38 to 40 0., and then gradually dimin- 

 ished. The individual predisposition of any ani- 

 mal to infectious disease seemed to stand in di- 

 rect relationship with the germicidal power of its 

 blood. A second series of researches was directed 

 to determining the influence of drugs on the pow- 

 er of the blood to destroy germs. From them the 

 author concluded that any drugs which caused 

 increased alkalinity of the blood considerably 

 raised the resisting power of the organ ism against 

 the inroads of bacteria. 



Respecting the detection of human blood. Dr. 

 Copeman, of St. Thomas's Medical School, has re- 

 marked that, as there are no chemical tests for 

 blood as such, the observer has to resort to the 

 microscope for evidence of the presence or ab- 

 sence of the colored corpuscles. The tests appli- 

 cable to the coloring matter are chemical, micro- 

 scopic, and spectroscopic. The guuiacum test is 

 readily applicable and trustworthy within certain 

 limits, but is also given with milk, pus, and 

 urine, and can not be accepted without corrobo- 

 ration. It is possible to mistake for blood a red 

 stain such, for example, as might be found on 

 linen through a red scarf having been worn upon 

 a part bathed with perspiration. This is the 

 more likely to take place because sweat is occasion- 

 ally charged with the coloring matter of the blood. 

 Ila'inin crystals may be obtained from a small 

 stain by dissolving the coloring matter in glacial 

 acetic acid, and, if the stain is an old one, adding 

 a crystal of sodium chloride. No reliance for dis- 

 tinction can be placed upon the relative size of 

 haemin crystals obtained from human blood and 

 those derived from the blood of other animals, for 

 in both cases the size depends largely upon vary- 

 ing conditions. The sizeof the red corpuscles like- 

 wise does not furnish a reliable test. As yet the 

 microscope enables us only to determine wit h cer- 

 tainty whether the blood is mammalian or not. 

 The old dictum of the physiological text-books 

 that the haemoglobin of human blood can not l>e 

 crystallized is contradicted. Dr. Copeman has 

 obtained crystals of it in from ten to forty-eight 

 hours. If arsenic is given to the patients fora 

 few days the hvmoglobin ceases to crystallize, 

 but begins to do so again when the arsenic treat- 

 ment is discontinued. Unman blood taken from 

 the stomachs of leeches which have fed upon it 

 will crystallize. The order of the apjwarance of 



crystallization varies in different animals. It - 

 curs more quickly in the Mood of the rat, guinea 

 pig. and squirrel than in that of the cat, dog. li< !-. 

 and man. The micro-spectroscopic tests are im- 

 portant. Exposure to air turns haemoglobin to 

 meth-ha?moglobin, and it is the spectrum of this 

 substance, which is peculiar, that is obtained from 

 old blood stains. The best spectrum given bv 

 blood is yielded by reduced hjematin. 5l on key's 

 blood crystallizes, so far as regards the oxidation 

 of the haemoglobin, exactly like man's a fact 

 which is not found to obtain in any other animal. 

 But human haemoglobin crystallizes rectangular- 

 ly, while monkers is diamond-shaped or six- 

 sided. The blood of many domestic animals re- 

 fu.-es to crystallize under the ordinary method 

 for human blood, but may be made to crystallize 

 by treatment with ether. The form of the < i \ - 

 tals in all other animals than man differs from 

 the rectangular prisms derived from human 

 blood, and they always consist of oxyhaemoglobin. 

 while in man and the monkey they "are formed of 

 reduced haemoglobin. As a positive exj>eri- 

 ment, human blood may be made to crystallize by 

 the addition of decomposing serum, by treatment 

 with solution of bile salts, by agitation with 

 ether, and by semidigestion in the stomach of 

 the leech. Of these, the first is to be recom- 

 mended as the best method. 



Dr. Lilienfeld has observed Prof. KosseFs 

 " histon " in the leucocytes of the blood, united to 

 nuclein as "nucleo-histon." Histon prevents the 

 clotting of blood, while nuclein promotes the for- 

 mation of fibrin. These two facts are regarded as 

 explaining the various phenomena connected 

 with blood clotting. Thus the blood is fluid in 

 the blood vessels because nucleo-histon is retained 

 bv the leucocytes. ( >n t he other hand, when the 

 blood is shed, some of the leucocytes or platelets 

 die, whereupon the nucleo-histon escapes into the 

 plasma, is decomposed by the calcium salts there 

 present into nuclein and histon, and the former 

 (nuclein) then causes clotting. These facts also 

 explain the action of calcium salts in promoting 

 clotting. 



Prof. Zuntz, having observed that strong mus- 

 cular exertion has a different effect on the alka- 

 linity of the blood in carnivora and herbivora, the 

 point was reinvestigated in the author's labora- 

 tory by Dr. Cohnstem, who found that the blood 

 of a dog at hard work on a treadmill showed no 

 alteration of alkalinity. The result was unaf- 

 fected by diet. During very prolonged exertion 

 the blood was finally found to possess an in- 

 creased alkalinity. Prof. Zuntz had found that 

 the power of the blood of dogs to absorb car- 

 bonic dioxide was practically unaltered by ex- 

 ercise, whereas in rabbits it was considerably 



lessened. 



In the case of an albuminous fluid discharged 

 through fistulous openings by a patient troubled 

 with a distention of lymphatics in the leg, Dr. J. 

 Munk has found the discharges though some- 

 times transparent, always milky after a meal 

 containing fat. It thus resembles chyle rather 

 than lymph, and probably really is chyle. At 

 least t wothirdsof the fat given at anv one meal re- 

 appeared in the fluid from the fistula. The time 

 In tore the appearance varied according to the 

 hardness of the fat. being longer with the harder 

 fats. Large doses of starch or sugar hardly in- 



