434 OF GENERATION AND DEVELOPMENT. 



CHAPTER XL 



OF GENERATION AND DEVELOPMENT. 

 1. General View of the Nature of the Process. 



778. THERE is no one of the functions of living beings, that distin- 

 guishes them in a more striking and evident manner from the inert 

 bodies which surround them, than the process of Generation. By this 

 function, each race of Plants and Animals is perpetuated ; whilst the 

 individuals composing it successively disappear from the surface of the 

 earth, by that death and decay which are the common lot of all. There 

 are certain tribes, in which the death of the parent is necessary for the 

 liberation of the germs from which a new race is to spring up. This 

 is the case, for example, in some of the simplest Cellular Plants ; in 

 which every cell lives for itself alone, and performs its whole series of 

 vital operations independently of the rest. But as, in more complex 

 organisms, we find certain cells set apart for Absorption, others for 

 Secretion, &c., so do we find a particular group of cells set apart for 

 Reproduction ; and these go through a series of changes peculiar to 

 themselves, without interfering with the general life of the structure. 

 It is in the Vegetable kingdom, that the essential character of the Ge- 

 nerative process can be best studied ; and we shall, in the first instance, 

 therefore, inquire into the nature and import of the principal pheno- 

 mena which it presents. 



779. If we take as our starting-point the simple cell in which the in- 

 dividuality of the lowest Algae seems to reside, we find that this cell, 



Various stages of development of Hcematococcus binalis- a, a, simple rounded cells; b, elongated cells, 

 the endochrome preparing to divide; c, c, cells in which the division has taken place; d, cluster of four cells 

 formed by a repetition of the same process. 



under the influence of light and warmth, and supplied with aliment, 

 multiplies itself to an extent that almost seems unlimited ; and this by 

 a process of duplication exactly analogous to that which has been al- 

 ready described ( 212) as taking place in Cartilage ; the chief difie- 



