DEGENERATION. 219 



fact upon us, and the history of animal development but repeats the 

 tale. From seed to seed-leaf, from seed-leaf to stem and leaves, from 

 simple leaves to flower, and from flower to fruit, there is exhibited a 

 natural progress in plant-existence, which testifies eloquently enough, 

 by analogy at least, to the existence of like tendencies in all other 

 forms of life. Similarly, in the animal host, progressive change is 

 seen to convert that which is literally at first " without form and void " 

 into the definite structure of the organism. A minute speck of pro- 

 toplasm on the surface of the o.^^^ a speck that is indistinguishable, 

 in so far as its matter is concerned, from the materies of the animal- 

 cule of the pool is the germ of the bird of the future. Day by day 

 the forces and powers of development weave the protoplasm into cells, 

 and the cells into bone and muscle, sinew and nerve, heart and brain. 

 In due season the form of the higher vertebrate is evolved, and pro- 

 gressive change is once more illustrated before the waiting eyes of 

 life-science. But the full meaning of most problems which life-science 

 presents to view is hardly gained by a merely cursory insj^ection of 

 what may be called the normal side of things. The by-paths of de- 

 velopment more frequently, perhaps, than its beaten tracks reveal 

 guiding clews and traces of the manner in which the progress in ques- 

 tion has come to pass. So, also, the side-avenues of biology open up 

 new phases of, it may be, the main question at issue, and may reveal, 

 as in the present instance, an interesting reverse to the aspects we at 

 first deem of sole and paramount importance. For example, a casual 

 study of the facts of animal development is well calculated to show 

 that life is not all progress, and that it includes retrogression as well 

 as advance. Physiological history can readily be proved to tend in 

 many cases toward backsliding, instead of reaching forward and up- 

 ward to higher levels. This latter tendency, beginning now to be bet- 

 ter recognized in biology than of late years, can readily be shown to 

 exercise no unimportant influence on the fortunes of animals and 

 plants. In truth, life at large must now be regarded as existing be- 

 tween two great tendencies the one progressive and advancing, the 

 other retrogressive and degenerating. Such a view of matters may 

 serve to explain many things in living histories which have hitherto 

 been regarded as somewhat occult and diflicult of solution ; while we 

 may likewise discover that the coexistence of progress and retrogres- 

 sion is a fact perfectly compatible with the lucid opinions and teach- 

 ings concerning the origin of living things which we owe to the genius 

 of Darwin and his disciples. 



A fundamental axiom of modern biology declares that in the de- 

 velopment of a living being we may discern a panoramic unfolding, 

 more or less complete, of its descent. " Development repeats descent " 

 is an aphorism which cultured biology has everywhere writ large over 

 its portals. Rejecting this view of what development teaches, the 

 phases through which animals and plants pass in the course of their 



