Presidknt's Address — .Srct. D. 149 



morphological lepiesentatives of detiuite chaiiictei-s, oi- (as has been 

 receiitlj' su<Joesteil by Farmer) of o;ronps of characters. Since all 

 somatic miclei are the direct descendants of the sexual nuclei by a 

 process of continuous halving, Weismann's conception of a permanent 

 germplasm, though it ma}' have to be somewhat modified, can on the 

 whole well be maintained with our present knowledge of the subject. 

 The study of the (|uestion of the innnunity of organisms (the founda- 

 tion of which, by the way, was laid by botanical investigators such as 

 De Bary) lias during recent years led through a side-issue to an un- 

 expected development, which has an important bearing on the question 

 of the constancy of species as well as on the inter-relationships of 

 species, of genera and of larger groups, and may perhaps even throw 

 some light on many difficult (|uestions of the doctrine of descent 

 generally. The study of the so-called luemolysins of various animals 

 and of tlie so-called precipitins has opened up a path by means of the 

 so-called biological methods not only to determine the blood relation- 

 ships between the various groups of organisms, but to show further 

 that each species is characterised by definite compounds. Hitherto 

 ordinary chemical methods have not, except in a coarse way, demon- 

 strated differences such as can be pnjved to exist b}' the use of the 

 ha3mol3'sins and precipitins, but no contradiction can be feared, when 

 we assert that definite chemical differences are at the bottom of the 

 reactions which enable us, ^._r/., to distinguish the blood of man from 

 the blood of an anthropoid ape, while at the same time these show 

 clear aflftnities which are absent when they are compared with the 

 bloods of animals further removed from them in zoological classifica- 

 tion. Innumerable instances drawn from the animal kingdom of a 

 similar nature are at our disposal. They emljrace all classes of 

 animals, and it is satisfactory to find that in the vegetable kingdom 

 similar conditions prevail. Here also the precipitin reaction is specific, 

 and at the same time indicates what we may also, for want of a better 

 term, call blood relationship. Thus in experiments conducted by 

 \V. Magnus and Hans Friedenthal, the pea and wheat, as was expected, 

 showed no affinity. The pea show^ed affinity to vetch, but not to 

 lupine : wheat showed affinity to rye, barley and Elynius areolar iu.'^, 

 but not to English rye-grass and oats. I may add, that the genus 

 Elyinus is usually placed next to Hordeum (barley) in our classifica- 

 tion of grasses. 



Before proceeding further, I should like to point out the practical 

 importance of these investigations. The precipitin tests are now 

 admitted before courts of law when the question of the origin 

 of bloodstains is to be decided, the microscope giving us no means of 

 deciding, e.g., with certainty, between different kinds of mammalian 

 blood. About sixteen years ago in a murder case tried in Grahams- 

 town, certain stains were discovered on the supposed murderer's cloth- 

 ing, and were submitted to Dr. Chew and myself. The man said they 



