CHAPTER X. 



PANGENESIS. 



A " provisional hypothesis" supplementiii<r "Natural Selection." — State- 

 ment of the hypothesis. — Dilticulty as to multitude of gemmules — as 

 to certain modes of reprofluction — as to formations Avithout the requi- 

 site gemmules. — Mr. Lewes and Professor Delpino. —Difficulty as to 

 developmental force of gemmules — as to their spontaneous fission. — 

 Pangenesis and Vitalism. — Paradoxical reality. — Pangenesis scarcely 

 .superior to anterior hypntheses. — BufFon. — Owen. — Herbert Spencer. 

 — "Gemmules" as mysterious as "physiological units." — Conclusion. 



In addition to the theory of " Natural Selection," by which 

 it has been attempted to account for the origin of species, 

 ]\Ir. Darwin has also put forward what he modestly terms 

 " a provisional hypothesis " (that of Pangenesis), by which 

 to account for the origin of each and every individual 

 form. 



Now, though the hypothesis of Pangenesis is no ne- 

 cessary part of " Natural Selection,'^ still any treatise on 

 specific origination would be incomplete if it did not take 

 into consideration this last speculation of Mr. Darwin's. 

 The hypothesis in question may be stated as follows : That 

 each living organism is ultimately made up of an almost 

 infinite number of minute particles, or organic atoms, 

 termed "gemmules," each of wliich has the power of 

 reproducing its kind. ^loreover, these particles are sup- 



