168 CHARLES DARWIN. 



This hypothesis assumes that each one of the count- 

 less cells of which the body of a higher animal is 

 composed throws off a minute gemmule which, with 

 those derived frOm other cells, exists in the body, 

 and when supplied with nutriment multiplies by 

 division. Each gemmule is capable of ultimate de- 

 velopment into a cell similar to the one from which it, 

 either directly or indirectly, arose. Each cell of the 

 body dispatches its representative, as it were, to each 

 single germ- cell, and this explains how it is that the 

 latter possess the power of reproducing the likeness 

 of the parent body. But the germ-cells also receive 

 dormant gemmules which may remain undeveloped 

 until some generation in the remote future. The 

 development of the gemmules into cells depends on 

 their union with the developing cells which precede 

 them in the order of growth. Gemmules are thrown 

 off during each stage of growth and during maturity. 



This hypothesis of pangenesis is so called be- 

 cause the whole body is supposed to produce the 

 elements from which new individuals arise, the 

 germ-cells being only the union of these elements 

 into clusters. 



The fact that hybrids may be produced by 

 grafting, that the pollen can act on the tissues of 

 the female plant, and the male germ-cells on the 

 future offspring of the female, implies that the re- 

 productive material can exist and the reproductive 

 processes take place in the tissues, and that they 

 are not confined to the germ-cells. 



