OPENING ADDEESS. 11 



There are heaps of such things waiting for investigation. 

 Such are the so-called special sense organs of invertebrates; 

 the so-called " pineal eye " of certain lizards lying in the 

 middle line and now concealed by the epidermis. This 

 last is a structure with a lens and a retina-like arrangement 

 of cells ; its whole formation, its connection with the 

 nervous system and the corroboration furnished by 

 palaeontological inquiry have led irresistibly to the con- 

 clusion that it is an eye. Yet the conclusion is an 

 inference unsupported by Physiological experiment, and 

 though probable justifiable, not necessarily so. Its 

 function has never been ascertained, and, as far as its 

 structure goes, it might possibly be a heat sensory organ 

 not a light one. 



Like structure, therefore, leads us to postulate like 

 function but the character of the function is an inference 

 to be verified or not by physiological methods, and by 

 these only. 



Second class of instances, inferring changing Function 

 from changing Structure. 



So far I have only referred to a definite structure and 

 the definite function associated with it. The whole 

 question of the correlation becomes more complicated 

 when we have to deal with a structure, which in the 

 course of its development undergoes a gradual meta- 

 morphosis, the inference being that the function undergoes 

 a similar change. 



Here again the inference may be justified by verification, 

 but without ascertaining the function it remains an 

 assumption, and a much greater one than was the case in 

 those instances just referred to. 



To illustrate this I might select almost any organ in 

 different stages of its development, but a very beautiful 



