258 THE DESCENT OF MAN, 



plainly with castrated males. Again, independently of 

 old age or disease, characters are occasionally transferred 

 from the male to the female, as when in certain breeds of 

 the fowl spurs regularly appear in the young and healthy 

 females. But in truth they are simply developed in the 

 female; for in every breed each detail in the structure of 

 the spur is transmitted through the female to her male off- 

 spring. Many cases will hereafter be given where the 

 female exhibits more or less perfectly characters proper to 

 the male, in whom they must have been first developed and 

 then transferred to the female. The converse case of the 

 lirst development of characters in the female and of trans- 

 ference to the male is less frequent; it will therefore be 

 well to give one striking instance. With bees the pollen- 

 collecting apparatus is used by the female alone for gather- 

 ing pollen for the larvae, yet in most of the species it is 

 partially developed in the males to whom it is quite useless, 

 and it is perfectly developed in the males of Bombus or the 

 humble-bee.* As not a single other Hymenopterous insect, 

 not even the wasp, which is closely allied to the bee, is 

 provided with a pollen-collecting apparatus, we have no 

 grounds for supposing that male bees primordially collected 

 pollen as well as the females; although we have some reason 

 to suspect that male mammals primordially suckled their 

 young as well as the females. Lastly, in all cases of rever- 

 sion characters are transmitted through two, three or many 

 more generations, and are then developed under certain 

 unknown favorable conditions. This important distinction 

 between transmission and development will be best kept in 

 mind by the aid of the hypothesis of pangenesis. Accord- 

 ing to this hypothesis every unit or cell of the boby throws 

 off gemmules or undeveloped atoms which are transmitted 

 to the offspring of both sexes and are multiplied by self- 

 division. They may remain undeveloped during the early 

 years of life or during successive generations; and their 

 development into units or cells, like those from which they 

 were derived, depends on their affinity for and union with 

 other units or cells previously developed in the due order 

 of growth. 

 Inheritance at Corresponding Periods of Life. This 



* H. Miiller, " Anwendung der Durwiu'scben Lehre," etc. Verb, 

 d. n. V. Jahrg. xxix, p. 42. 



