216 THE INDUCTIONS OF BIOLOGY. 



There is, however, nothing for us but a choice of imperfec- 

 tions. We cannot by any logical dichotomies, accurately 

 express relations which, in Nature, graduate into each other 

 insensibly. Neither the above, nor any other scheme, can do 

 more than give an approximate idea of the truth. 



§ 76. Genesis under every form, is a process of negative 

 or positive disintegration ; and is thus essentially opposed to 

 that process of integration, which is one element of individual 

 evolution. Negative disintegration occurs in those cases 

 where, as among the compound Hydrozoa, there is a con- 

 tinuous development of new individuals by budding from the 

 bodies of older individuals ; and where the older individuals 

 are thus prevented from growing to a greater size, or reach- 

 ing a higher degree of integration. Positive disintegration 

 occurs in those cases of agamogenesis where the formation 

 of new individuals is discontinuous, and in all cases of gamo- 

 genesis. The degrees of disintegration are various. At 

 the one extreme, the parent organism is completely broken 

 up, or dissolved into new individuals ; and at the other 

 extreme, the new individual forms but a small deduction 

 from the parent organism. Protozoa and Protophyta, show 

 us that form of disintegration, called spontaneous fission : 

 two or four individuals being produced by the splitting-up 

 of the original one. The Vohox and the Hydrodictyon, 

 are plants which, having developed broods of young plants 

 within themselves, give them exit by bursting ; and among 

 animals, the one lately referred to, which arises from the 

 Distoma egg, entirely loses its individuality in the individ- 

 ualities of the numerous Distoma-larvad with which it be- 

 comes filled. Speaking generally, the degree ot 

 disintegration becomes less marked, as we approach the higher 

 organic forms. Plants of advanced types throw off from 

 themselves, whether by gamogenesis or agamogenesis, parts 

 that are relatively small; and among the higher animals, 

 there is no case in which the parent individuality is habitually 



