X.] PANGENESIS. 249 



quires nothing of the kind, but explains the evolution of 

 each individual by purely mechanical conceptions. In 

 fact, however, it is not so. Each gemmule, according to 

 Mr. Darwin, is really the seat of powers, elective affinities, 

 and special tendencies as marked and mysterious as those 

 possessed by the physiological unit of Mr. Spencer, with 

 the single exception that the former has no tendency to 

 build up the whole living, complex organism of which it 

 forms a part. Some may think tliis an important distinc- 

 tion, but such can hardly be the case, for Mr, Darwin con- 

 siders that his gemmule has the innate power and tendency 

 to increase and transform itself into the whole living, com- 

 plex cell of which it forms a part; and the one tendency is, 

 in principle, fully as difficult to understand, fully as mys- 

 terious, as the other. The difference is but one of degree, 

 not of kind. Moreover, the one conception in the case 

 of the "physiological unit" explains all, while with regard 

 to the gemmule, as we have seen, its power of growth has 

 to be supplemented by other powers and tendencies, each 

 distinct, and each in itself inexplicable and profoundly 

 mysterious. 



That there should be physiological units possessed of 

 the power attributed to them, harmonizes with what has 

 recently been put forward by Dr. y. Charlton Bastian ; ^ 

 who maintains that under fit conditions the simplest 

 organisms develop themselves into relatively large and 

 complex ones. This is not supposed by him to be due 

 to any inheritance of ancestral gemmules, but to direct 



^ As this sheet of the second edition is passing through the press, a 

 work has appeared written by Dr. H. Charlton Bastian, and entitl 

 "The diodes of Origin of Lowest Organisms." London and New York : 

 Macmillan and Co. 



