THE CHARACTERISTICS OF ORGANISMS 25 



the ovary of the flower, a miniature plant is formed by the division 

 and re-division of the fertiUsed egg-cell. The ovule becomes a seed; 

 and this, when sown, a seedling. By insensible steps there is fashioned 

 a large and varied fabric, of root and shoot, of leaves and flowers. 

 But sooner or later, after this development is complete, the grass 

 begins to wither and the flower thereof to fade. In the case of an 

 annual plant, there is soon nothing left but the seeds, which begin 

 the cycle anew. It is, Huxley said, "a Sisjrphean process, in the 

 course of which the living and growing plant passes from the 

 relative simplicity and latent potentiality of the seed to the full 



Fig. 8. 



Dogfish Egg-case or Mermaid's Purse. From a specimen. The horny shell is 

 drawn out at the four corners into tendrils (T) which automatically 

 moor the egg to seaweed, zoophyte, or the like, thus preventing smother- 

 ing. The young fish shows the yolk-sac {ys) entering the food-canal by 

 a hollow stalk (st) . On the neck region there are external gills (eg) ; on the 

 back a dorsal fin {df). 



epiphany of a highly differentiated type, thence to fall back to 

 simplicity and potentiality again." 



Similarly, among animals the egg-cell, in many cases micro- 

 scopic, divides and re-divides, and an embryo is built up. Division 

 of labour sets in among its units, and the structural side of this is 

 differentiation. The hereditary initiatives, implicited in some way 

 that we cannot image, are activated, and out of the apparently 

 simple there emerges the obviously complex. The latent becomes 

 patent, the implicit becomes explicit, the invisible becomes visible. 

 Some cells become nervous, others muscular, others glandular, 

 others skeletal; and so the differentiating process continues. 

 Hereditary contributions from parents and ancestors find expres- 



