84 PRIMITIVE FORMS OF LIFE 



influences derived from external environment or from neigh- 

 bours which pervade and penetrate it with their excretory 

 products, continually modifying even their common medium 

 to suit their nutritive needs ; then nothing would be more 

 natural than that considerable variety should therefore develop 

 in the characters and properties of the elements associated in 

 the same body. Furthermore, from this variety there would 

 naturally arise among the inter-related elements a more or less 

 notable degree of solidarity, since, though each organism lives 

 for its own sake, the medium or ensemble in which they live is 

 their common achievement, and can scarcely be reconstructed 

 without them. But when a group of elements capable of living 

 together and multiplying, or a single element, the egg, capable 

 of absorbing nourishment and multiplying in an independent 

 fashion, becomes detached from this association, how does it 

 happen that the new elements become diversified, and in both 

 cases, whatever the external conditions may be, are grouped 

 in such a way as to form another organism similar in all its 

 details to that from which they were separated originally ? 



With regard to this point, we are forced back upon 

 hypotheses whose phenomena, however, may be submitted 

 to close analysis, thus circumscribing the ground we have to 

 cover. Every modification affecting any predetermined part 

 of the body expresses itself in a change either in the constitution 

 of its elements or of their mode of nutrition, activity or number. 

 In every case the products excreted are themselves changed 

 qualitatively or quantitatively. These products can be poured 

 directly into the interior " environment ", i.e. into the blood, 

 or the liquid that takes its place in the lower animals, and this 

 environment then experiences a modification correlative to that 

 of the portion of the body modified. These products may also 

 pass immediately into contiguous elements, which they modify, 

 and which in their turn modify the parts with which they are in 

 contact ; and these modifications may then proceed, stage by 

 stage, till they reach the reproductive cells, which in the first 

 case are modified at the beginning because of their immersion 

 in an interior medium itself having undergone modification. 

 However, it is difficult to admit that so intimate a correlation 

 exists between the interior medium and the various parts of 

 the body, that the modifications of the latter should be re- 

 echoed in the reproductive cells through the agency of this 



