THE PROVISIONAL HYPOTHESIS OF PANGENESIS. 303 



come converted into the various tissues and substances of 

 the body. But besides this means of increase I assume 

 that the units throw off minute granules which are dis- 

 persed throughout the whole system ; that these, when 

 supplied with proper nutriment, multiply by self-division, 

 and are ultimately developed into units like those from 

 which they were originally derived. These granules may 

 be called gemmules. They are collected from all parts 

 of the system to constitute the sexual elements, and their 

 development in the next generation forms a new being ; 

 but they are likewise capable of transmission in a dormant 

 state to future generations and may then be developed. 

 Their development depends on their union with other 

 partially developed or nascent cells which precede them 

 in the regular course of growth. Why I use the term 

 union will be seen when we discuss the direct action of 

 pollen on the tissues of the mother-plant. Gemmules 

 are supposed to be thrown off by every unit, not only 

 during the adult state, but during each stage of develop- 

 ment of every organism ; but not necessarily during the 

 continued existence of the same unit. Lastly, I assume 

 that the gemmules in their dormant state have a mutual 

 affinity for each other, leading to their aggregation into 

 buds or into the sexual elements. Hence, it is not the 

 reproductive organs or buds which generate new organ- 

 isms, but the units of which each individual is composed. 

 These assumptions constitute the provisional hypothesis 

 which I have called pangenesis. 



_ OM But I have further to assume that the 



Page 372. 



gemmules in their undeveloped state are capa- 

 ble of largely multiplying themselves by self-division, 

 like independent organisms. Delpino insists that to 

 "admit of multiplication by fissiparity in corpuscles, 



