Chap. XXVIL OF PANGENESIS. 385 



• 



But this explanation hardly applies to those plants which 

 naturally produce a multitude of seeds, but which, through a 

 comparatively small increase in the number of the buds on 

 their rhizomes or offsets, yield few or no seed. As, however, 

 we shall presently see that buds probably include tissue which 

 has already been to a certain extent developed or differentiated, 

 some additional organised matter will thus have been expended.' 

 From one of the forms of Eeproduction, namely, spontaneous 

 self-division, we are led by insensible steps to the repair of the 

 slightest injury ; and the existence of gemmules, derived from 

 every cell or unit throughout the body and everywhere diffused 

 explains all such cases,— even the wonderful fact that, when the 

 limbs of the salamander were cut off many times successively 

 by bpallanzani and Bonnet, they were exactly and completely 

 reproduced. I have heard this process compared with the re- 

 crystalhsation which occurs when the angles of a broken crystal 

 are repaired; and the two processes have this much in common 

 that in the one case the polarity of the molecules is the efficient 

 cause, and in the other the affinity of the gemmules for par- 

 ticular nascent cells. 



Pangenesis does not throw much light on Hybridism, but 

 agrees well with most of the ascertained facts. We may con- 

 clude from the fact of a single spermatozoon or pollen-grain 

 being ^sufficient for impregnation, that a certain number of 

 gemmules derived from each cell or unit are required for the 

 development of each part. From the occurrence of parthe- 

 wirthl T GSPeCi f J " th6 — ° f ^ ^-moth, m 



of all k tr f T' m ; 1UdeS —% -ffi^ent gemmules 



— witMh^ - that when 



abundant. Now as a iZ l ^^ """' be mp6T ' 

 are cro^r] P • n g al mle ' when two s P ecies or races 



are crossed reciprocally, the offspring do not differ and this 

 shows that both sexual element* 



with thP vipw *i TT ements a g r ee in power, in accordance 

 with the view that they include the same gemmules. Hybrids 



pa IZZT^Xt ° CC f° Da% *°* ^ ™ We -e 



2 c 



