THE DOCTRINE OF IMMORTALITY 47 



A special form of division is budding, which plays an im- 

 portant role, especially among the hydroids. The process is 

 described in all text-books, and need therefore be mentioned 

 merely. A little superficial group of cells begins to grow and 

 forms finally a new polyp. 



In the cases considered thus far, a number of cells partici- 

 pate in the propagation. In the case of the so-called partheno- 

 genesis the creation of a new individual starts from a single 

 cell. This cell is an egg, which develops without being fer- 

 tilized. Great interest was excited by the discovery of artifi- 

 cial parthenogenesis by A. C. Mead. 20 In the artificial devel- 

 opment we utilize chemical action which replaces fertiliza- 

 tion proper, and so excites the ovum that it develops further. 



In all these cases the propagation is effected by the separa- 

 tion of living material from the body of a living individual. 

 The separated substance remains continuously alive. The 

 substance may be comprised of many, several, or only one 

 cell. The number of cells is unessential; essential is only 

 that the substance is alive and remains alive. 



The separated substance inherits the primitive organiza- 

 tion, or, more exactly expressed, has the parental organiza- 

 tion, because it is unaltered parental substance. We come 

 up against a question which we unfortunately cannot yet 

 answer : How is the organization regulated ? It seems a matter 

 of indifference how the asexual propagation is accomplished. 

 Each time the development proceeds, until the original 

 organization is completed. When the budding zone of anne- 

 lids forms a new tail in the anterior part of the animal and a 

 new head for the posterior part, we can only say that a regula- 

 tion of the organization is shown. There is no means for 

 determining more exactly the process. It seems to be clear that 

 this regulation is not to be sought only in the developing cells 



