344 COSMIC PIIILOSOPn F. [pt. ii. 



cats it up as effectually as a carnivorous enemy could 

 eat it. To employ an instinctive metaphor, a cancer is a 

 rebellion within the organism, — a setting up of an indepen- 

 dent centre of government, — a fatal iuterference with the 

 subordination of the parts to the whole. Yet the organism 

 in which a cancer has begun to grow is mure heterogeneous 

 than the healthy organism. In like manner the first stages 

 of decomposition increase the heterogeneity of the organism 

 as a whole ; but because each new retrograde product follows 

 henceforth a career of its own, i'ree from the control of the 

 organic aggregate, the result is not evolution, but dissolution. 

 The differentiations which occur during tire normal growth 

 of the germ, differ from those which constitute cancer and 

 gangrene, alike in their common subordination to the pri- 

 mary process of growth, and in the deiiniteness of the 

 resulting structures. " In the mammalian embryo, the heart, 

 at first a long pulsating blood-vessel, by and by twists upon 

 itself and integrates. The bile-cells constituting the rudi- 

 mentary liver, do not simply become different from the wall 

 of the intestine in which they at first lie ; but as they 

 accumulate, they simultaneously diverge from it, and con- 

 solidate into an organ. The anterior segments of the cerebro- 

 spinal axis, which are at first continuous with the rest, and 

 distinguished only by their larger size, undergo a gradual 

 union ; and at the same time the resulting head folds into a 

 mass clearly marked off from the rest of the vertebral column. 

 The like process, variously exemplified in other organs, is 

 meanwhile exhibited by the body as a whole; which be- 

 comes integrated somewhat in the same way that an outspread 

 handkerchief and its contents become integrated when its 

 edses are drawn in and fastened to make a bundle." Mr. 

 Spencer, from whom I have quoted this embryologic illus- 

 tration, goes on to cite parallel instances in the development 

 of lower forms of animal life ; a few of which may be here 

 epitomized. In the growth of the lobster from its embryo, a 



