BLOOD RELATIONSHIPS 411 



from a knowledge of the comparative anatomy and embryology, 

 and from the palaeontology regarding these three species. 



The precipitin blood-tests therefore furnish a means for 

 estimating the relative similarities between the bloods of 

 different animals, and they are not only a biochemical proof 

 of the theory of evolution, but also an index for classification. 



The following are a few tables showing the relative affinities 

 between the bloods of a number of vertebrates : * 



Anti-human serum, mixed with blood of : — 



These results show several interesting points. In the first 

 place, the great similarity between the blood of man and that 

 of the gorilla should dispel any doubt (should any be left) 

 concerning the evolution of man from lower mammals. The 

 precipitation percentages show that human blood is more like 

 that of the apes than that of the baboon, and more like the 

 latter than the blood of animals like horse and deer. This 

 fits in perfectly with evidence derived from other sources. 

 It is also interesting to note that two animals which are believed 

 to be closely related to one another like ox and sheep, should 

 show the same degree of dissimilarity to man. The relation- 

 ship between sheep and ox can also be tested by immunising 

 a rabbit to sheep blood . 



Anti-sheep serum mixed with blood of : — 



Sheep gives ioo per cent, precipitation. 



Ox „ 75 



Antelope ,, 67 „ ,, 



Reindeer ,, 35 „ „ 



The relationship between sheep and ox is here definitely 

 shown to be close. 



* FromNuttall. 



