68 THE PROBLEM OF EVOLUTION 



chemical and physiological resemblance between two 

 kinds of blood as constituting a blood-relationship in 

 the sense of having a common origin. Let us assume 

 that there is a resemblance between the blood of 

 apes and that of men. This would prove that the 

 same kind of likeness exists in the blood of men 

 and apes, as in their skeletons and other organs. 

 But similarity of blood does not imply blood- 

 relationship, such as exists between cousins and 

 kinsfolk. Rossle has recently brought out an inter- 

 esting work on this subject (in the Biologisches 

 Zentralblatt for 1905, Nos. 11 and 12). He is 

 of opinion that the blood-reaction only enables us 

 to say that one animal is more closely related to 

 another than to a third, but it does not show how 

 closely any two animals are related. From his 

 point of view therefore the blood-reaction between 

 man and the higher apes does not justify the 

 conclusion that they are closely related, still less 

 that man ought to be classed with the higher apes. 

 He also insists upon the fact that the chemical 

 composition of the fluids of the body, such as the 

 blood, is no more constant than, for instance, the 

 formation of the skeleton, therefore evidence based 

 on resemblance of the blood is no more trustworthy, 

 in support of a common descent, than that based on 

 similarities of the skeleton and other morphological 

 resemblances. In fact, it has been ascertained that 

 in many cases similarity in the blood does not 

 correspond with morphological resemblance, and the 



