610 SCIENTIFIC THOUGHT. 



speculation of Darwin's which he put forward at the 



end of his work on ' The Variation of Animals and 



Plants under Domestication' (1868) the theory of 



88. " Pangenesis." " This hypothesis implies that the whole 



"Pwi- 



genesi." organisation, in the sense of every separate atom or unit, 

 reproduces itself. Hence ovules and pollen grains, the 

 fertilised seed or egg as well as buds, include and consist 

 of a multitude of germs thrown off from each separate 

 atom of the organism." l These germs he calls gem- 

 mules, and admits that they agree to some extent with 

 Buffon's organic molecules, only that neither in these nor 

 in Spencer's physiological units does it seem clear that 

 each "independent or autonomous" organic unit, say 

 each cell, throws off or contributes its free gemmule (or 

 gemmules), which is capable of reproducing a similar 

 cell. 2 



The theory of Pangenesis has not found much favour 

 with biologists. 3 For their purposes it would be neces- 



1 Loc. cit., vol. ii. p. 358. casts off a free gemmule, which is 



2 " Physiologists agree that the capable of reproducing a similar 

 whole organism consists of a inulti- cell" (p. 377). "As each unit, or 

 tude of elemental parts, which are group of similar units throughout 

 to a great extent independent of the body, casts off its gemmules, 

 each other" (toe. cit., voL ii. p. and as all are contained within the 

 368). Darwin then quotes Claude smallest egg or seed, and within 

 Bernard (1866) and Virchow (1860) each spermatozoon or pollen-grain, 

 on the doctrine of the " autonomy " their number and minuteness 

 of cells : " I assume that the gem- must be something inconceivable " 

 mules in their dormant state have (p. 378). 



a mutual affinity for each other, 

 leading to their aggregation either 

 into buds or into the sexual ele- 

 ments" (p. 374). "Physiologists 

 maintain, as we have seen, that 



Grant Allen dismisses the 

 whole speculation in the fol- 

 lowing words : " The volume on 

 the variation of animals and 

 plants contained also Darwin's one 



each cell, though to a large extent | solitary contribution to the pure 

 dependent on others, is likewise, to speculative philosophy of life his 

 a certain extent, independent or ' ' Provisional Hypothesis of Pan- 

 autonomous. I go one small step genesis,' by which he strove to 

 farther, and assume that each cell account, on philosophical principles, 



