EVIDENCE FROM BLOOD TESTS 79 



(8) Anti-lizard serum produces maximum results 

 with the bloods of lizards and reacts well with those 

 of snakes. 



(9) These experiments indicate that there is a 

 close relationship between lizards and snakes, on the 

 one hand, turtles and crocodiles, on the other. They 

 further indicate that birds are more nearly allied 

 with the turtle-crocodile series than with the lizard- 

 snake series, results for which palaeontogical studies 

 had already prepared us. 



(10) "Tests were made by means of anti-sera for 

 the fowl and ostrich upon 792 and 649 bloods respec- 

 tively. They demonstrate a similarity in blood con- 

 stitution of all birds, which was in sharp contrast to 

 what had been observed with mammalian bloods, 

 when acted upon by anti-mammalian sera. Differ- 

 ences in the degree of reaction were observed, but 

 did not permit of drawing any conclusions." 



(11) I have already called attention to the fact 

 that the problematical Horseshoe-crab is indicated 

 by its embryology to be related to the air-breathing 

 spiders and scorpions rather than to the marine 

 Crustacea. It is of exceptional interest to learn 

 that embryology is supported by the results of the 

 blood-tests. 



It must not be supposed that there is any exact 

 mathematical ratio between the degrees of relation- 

 ship indicated by the blood tests and those which 

 are shown by anatomical and palseontological evi- 

 dence. Any supposition of the kind would be imme- 



