76 THE THEORY OF EVOLUTION 



was taken, the blood of nearly allied species, such as 

 the horse and donkey, for example, gives a weaker 

 and slower precipitation. By using stronger solu- 

 tions and allowing more time, quite distant relation- 

 ships may be brought out. Nuttall and his collabo- 

 rator, Graham-Smith, made many thousands of such 

 experiments bearing upon the problems of relation- 

 ship and classification and it is of great significance 

 to note that their highly interesting and important 

 results contain few surprises, but, in almost all cases, 

 merely serve to confirm the conclusions previously 

 reached by other methods, such as comparative 

 anatomy and palaeontology. It will be instructive 

 to quote some of these results, the quotations being 

 taken from "Blood Immunity and Blood Relation- 

 ship by G. H. F. Nuttall, including Original Re- 

 searches by G. L. Graham-Smith and T. S. P. 

 Strangeways;" Cambridge, 1904. 



"In the absence of palaeontological evidence the 

 question of the interrelationship amongst animals 

 is based upon similarities of structure in existing 

 forms. In judging of these similarities, the subjec- 

 tive element may largely enter" (p. 1). "The very 

 interesting observations upon the eye made by 

 Johnson also demonstrate the close relationships 

 between the Old World forms and man, the macula 

 lutea tending to disappear as we descend in the scale 

 of New World monkeys and being absent in the 

 Lemurs. The results which I published upon my 

 tests with precipitins directly supported this evi- 



