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Proceedings of the Royal Society of Edinburgh. [Sess. 
equivalent to those achieved by chemistry, by physics, and by morphology. 
Indeed, apart from the line taken by c ‘ general physiology,” it is hard 
to see whither the study of physiology as a coherent body of science is 
tending. 
To discourage study of invertebrate physiology in the interests of 
human physiology is certainly a mistake. From a union of physiology 
with comparative morphology there is much to be looked for ; prima facie 
it is a great piece of fortune for the physiologist to have the ground 
so well charted by the morphologists. In the more recent books on 
comparative physiology the arrangement of subject-matter is strictly 
according to physiological activities. This change, while dictated by 
ideals of consistency, may be only a make-believe improvement in the 
interests of the whole subject. Just as in Wiedersheim’s Comparative 
Anatomy (where the classification of matter is designed on strictly 
morphological lines), we find chapters with headings like these, “ Organs 
of Nutrition,” “ Organs of Circulation,” etc. ; so in books on comparative 
physiology it might still be an advantage to drop the wider physiological 
and to employ an anatomieo-functional arrangement. 
Suppose we had a book that treated of the integument in all its 
physiological aspects, and similarly of other common organs (there are 
“ tcl Twv irTepvyccv to. re tcov (tkgXwv ”) 5 without doubt such a book would 
bring a flood of light to bear upon the relation between structure and 
function; for, however much we may abstract structure from function 
and function from structure, when it comes to be a question of structural 
development, physiology and morphology are indivisible. 
Simply to show how far we have already travelled I shall quote the 
following sentences from Wiedersheim (1886): — “ The closely allied branches 
of science defined above are united together as Morphology , as opposed to 
Physiology , which concerns the functions of organs, apart from their 
morphological relations. Morphology alone leads us to a satisfactory 
explanation of the structural phenomena of the animal body, for it not 
only reveals to us the law of heredity and the consequent relationship of 
animals to one another, but, etc.” 
I wish to offer my thanks to Mr R. K. S. Lim of Singapore for making 
the drawings and diagrams that accompany this paper. 
The expenses of the research were defrayed by a grant from the Earl 
of Moray Fund for the prosecution of research in the University of 
Edinburgh. 
