Chap. XXVII. OF PANGENESIS. 403 



remarked, number and size are only relative difficulties and 

 the eggs or seeds produced by certain animals or plants are so 

 numerous that they cannot be grasped by the intellect. 



The organic particles with which the wind is tainted over 

 miles of space by certain offensive animals must be infinitely 

 minute and numerous; yet they strongly affect the olfactory 

 nerves. An analogy more appropriate is afforded by the con- 

 tagious particles of certain diseases, which are so minute that 

 they float in the atmosphere and adhere to smooth paper ; yet 

 we know how largely they increase within the human body, and 

 how powerfully they act. Independent organisms exist which 

 are barely visible under the highest powers of our recently- 

 improved microscopes, and which probably are fully as large 

 as the cells or units in one of the higher animals ; yet these 

 organisms no doubt reproduce themselves by germs of extreme 

 minuteness, relatively to their own minute size. Hence the diffi- 

 culty, which at first appears insurmountable, of believing in 

 the existence of gemmules so numerous and so small as they 

 must be according to our hypothesis, has really little weight. 

 ^ The cells or units of the body are generally admitted by phy- 

 siologists to be autonomous, like the buds on a tree, but in a 

 less degree. I go one step further and assume that they throw off 

 reproductive gemmules. Thus an animal does not, as a whole, 

 generate its kind through the sole agency of the reproductive 

 system, but each separate cell generates its kind. It has 

 often been said by naturalists that each cell of a plant has the 

 actual or potential capacity of reproducing the whole plant; but 

 it has this power only in virtue of containing gemmules derived 

 from every part. If our hypothesis be provisionally accepted, we 

 must look at all the forms of asexual reproduction, whether oc- 

 curring at maturity or as in the case of alternate generation 

 during youth, as fundamentally the same, and dependent on the 

 mutual aggregation and multiplication of the gemmules. The 

 regrowth of an amputated limb or the healing of a wound is the 

 same process partially carried out. Sexual generation differs in 

 some important respects, chiefly, as it would appear, in an insuf- 

 ficient number of gemmules being aggregated within the separate 

 sexual elements, and probably in the presence of certain primor- 

 dial cells. The development of each being, including all the 



2 d 2 



