PliESIDENT's ADDRESS. 23 



misconceived, when it is stated as follows : — " The ground idea of 

 the new anatomy was evidently that of the existence of an imma- 

 nent type or plan which an organism or group of allied organisms 

 adheres to thr-ough every variety of outward modification. 

 This idea dominates morphology and differentiates it from other 

 sciences, just as the ideas of matter and energy dominate and 

 differentiate phj^sics." Such a statement of morphological faith 

 might indeed have emanated from such a scientific anatomist as Sir 

 Richard Owen, but it will certainly not symbolise the practically 

 unanimous views of more recent morphologists. For them, 

 *' immanent type or plan" undoubtedly resolves itself into a com- 

 munity of structural character due to actual blood-relationship ; 

 an ideal "adherence to morphological plan" is reducible simply 

 to community of origin. 



This view of the essential nature of "homology" will alone 

 afford a rational explanation of detailed morphological relation- 

 ships. According to Dr. Haldane the conception of each part of 

 an organism, regarded morphologically, " evidently involves the 

 conception of its morphological relationships to other parts." In 

 other words, the conception of each part involves that of the 

 whole. "We can mentally separate the parts of a j^bysical 

 structure from the other parts of the same structure, but we can- 

 not do so with the parts of a morphological structure." But 

 whenever we seek to translate into detail what the actual 

 morphological relationships of parts signify, i.e., from the 

 strictly morphological point of view, and apart from their 

 functional significance, we find that we interpret these relation- 

 ships systematically from the point of view of a theory of descent, 

 and not from that of the existence of "an immanent type or 

 plan " to which the organism " adheres through every variety of 

 outward modification." No doubt "the method of comparing 

 different organisms and different stages in the development of the 

 same organism enables the morphologist to perceive a definite cor- 

 relation among the parts," but the guiding hypothesis with which 

 he is armed when endeavouring to read unity into the diversity 

 of structural modification — to discover true morphological 



