THE EVIDENCE FROM DEGENERATION. 363 



probably we shall find the solution of such conditions to exist 

 within the operation of some deep-seated law of the living constitu- 

 tion, and in the effects of that law in moulding or even contorting 

 the animal frame. 



It constitutes one of the chief glories of biological science, as 

 pursued amongst us to-day, that its studies are of far-reaching order, 

 and lead, as the results of their natural extension, to the considera- 

 tion of fields of thought often widely removed from the original topic 

 which interests the reader. The present subject of degenerative 

 changes, regarded as part and parcel of the living constitution, can 

 readily be shown to possess applications far removed from zoology 

 and botany, and extending into the most intimate spheres and phases 

 of human history itself. Degenerative change in human tissues is 

 medically symptomatic of very many of the ills to which flesh is heir. 

 Tissues and organs degenerate in individual animals, as animal frames 

 retrogress in their entirety. Cells retrograde and fibres degenerate 

 in our bodies, just as the sea-squirt's frame exhibits, as a whole, a 

 universal physiological backsliding. Nor may many of our diseases 

 alone be esteemed mere examples of degeneration affecting our 

 tissues. The termination and decline of life itself, and the age that 

 really " melts in unperceived decay," are in reality examples of natural 

 degeneration also. The decline of existence is largely a retrogression 

 of structure. There can be no such thing as a really "green old 

 age," any more than we can speak of " the sere and yellow " of the 

 autumnal leaf as imitating the verdant nature of the spring blossom. 

 Nay, stranger still is it to discern that the full flush of life's vigour is 

 accompanied by degenerative changes as typical as those which mark 

 life's decline. For every tissue wastes as it works; and cells degenerate, 

 die, and are cast off from every surface and tissue of our frames as 

 the natural result of living and being. " Generally speaking," says 

 a writer in discussing the degeneration of human tissues, " those 

 parts which live most slowly are those of which the duration is the 

 greatest, and in which there is consequently the least frequent change. 

 Of the exuviation of epidermic structures en masse a process 

 altogether comparable to the fall of the leaf we have striking 

 examples in the entire desquamation of serpents, the moulting of 

 the plumage in birds, and the shedding of the hair in mammalia ; 

 and in the shedding of the antlers of the stag we have an example 

 of the exuviation of a highly organised and vascular part, which 

 periodically dies, and which, being external, is cast off entire. ' What 

 means all this,' says Sir James Paget, ' but that these organs have 

 their severally appointed tissues, degenerate, die, are cast away, and 

 in due time are replaced by others, which in their turn are to be 

 developed to perfection, to live their life in the mature state, and to 

 be cast off?'" And, again, the same high authority remarks that 



