228 The Descent of Man. Past II. 



in the structure of the spur is transmitted through the female 

 to her male offspring. 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 first de- 

 velopment of characters in the female and of transference to the 

 male, is less frequent ; it will therefore be well to give one strik- 

 ing instance. With bees the pollen-collecting apparatus is used 

 by the female alone for gathering 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. 32 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 

 reversion, characters are transmitted through two, three, or many 

 more generations, and are then developed under certain unknown 

 favourable conditions. This important distinction between 

 transmission and development will be best kept in mind by the 

 aid of the hypothesis of pangenesis. According to this hypothesis, 

 every unit or cell of the body 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 tendency 

 is well established. A new character, appearing in a young 

 animal, whether it lasts throughout life or is only transient, will, 

 in general, reappear in the offspring at the same age and last 

 for the same time. If, on the other hand, a new character 

 appears at maturity, or even during old age, it tends to re- 

 appear in the offspring at the same advanced age. When devia- 

 tions from this rule occur, the transmitted characters much 

 oftener appear before, than after the corresponding age. As I 

 have dwelt on this subject sufficiently in another work, 33 I will 



32 H. Mulls i", ' Anwenduag der 33 ' The Variation of Animals 



Darwin'schen Lehrt,' &c. Verh. and Plants under Domestication,' 

 d. n. V. Jahvg. xxix. p. 42. vol. ii. 1868, p. 75. In the last 



