ON BIOLOGY. 81 



known. Several of the structures and organs of our 

 bodies are still enigmas to us in so far as we have been 

 enabled to appreciate their morphological significance. 

 The same strictures apply to the functions or to the 

 physiology of those organs. Much in the developmental 

 and homological history of man's skeleton is still obscure, 

 and especially is this true of the skull. Even in ap- 

 parently so simple a system as the muscular, or in the 

 case of the ligaments, we still are presented with prob- 

 lems that up to the present time have remained unsolved. 

 Still greater difficulties have been met in the case of some 

 of the structures of the brain and general nervous sys- 

 tem; in the suprarenal capsules, the thyroid and thymus 

 glands; the spleen; special structures of the eye, ear and 

 tongue; and, indeed, the list when taken as a whole, is, 

 as I have just said, not a short one. 



Now if this be the case with man, it is not difficult to 

 imagine how vast must yet be the store of facts still un- 

 revealed in the entire range of the morphology of all other 

 animals and plants apart from him. As I have stated 

 several times we are in possession of the main fundamen- 

 tal plan of structure that characterizes animals in Nature 

 to be sure, yet how ignorant we still are of the well-nigh 

 limitless array of the details of structure. And it is the 

 discovery of the presence and meaning of these special 

 structural details in certain forms which will explain not 

 only the morphological significance of the obscure points 

 in man's anatomy, but the corresponding ones in all those 

 other animals wherein the new structure is found to 

 exist. 



Permit me to present you with one or two examples 

 exhibiting the manner in which the discovery of new 

 structures in the lower animals not only throws light 

 upon the corresponding structures in allied forms, but 

 also often upon the most obscure points in the anatomy 

 of man. Now there is a small, glandular structure at 

 the base of the brain in all men, and in all mammals, so 

 far as I can recollect, which bears the name of the pineal 

 gland. Until within a very recent time the uses of this 

 structure were entirely unknown, and not a work upon 

 either human anatomy or physiology threw any light 

 upon the subject. Descartes supposed it to be the seat 

 of the soul! But the nineteenth century biologist knows 

 better than that, at least; for, thanks to the researches of 

 Baldwin Spencer, of England, made in 1886, we have, I 

 think, a better solution of the case. Mr. Spencer, in 

 making dissections upon that unique form of lizard from 



