darwin's theory of pangenesis. 107 



by a graft would certainly be affected by the gem- 

 mules arising in the root and body of the stock. 

 Such is not the case in many instances. Pips from 

 a pear grafted on a quince-stock will not give rise to 

 a hybrid between a pear and a quince. The stone 

 of a peach grafted on a plum-stalk will not grow into 

 a tree whose stalk bears plums while the extremities 

 of the branches bear peaches. 



The gemmules of the quince are thrown through 

 the walls of the cells in the scion of the pear ; they 

 circulate in its sap, and we should suppose that they 

 would produce a hybrid. But they do not. We 

 know they circulate in the scion, if they are as small 

 as they must be according to this theory. But we 

 cannot trace them by the effects the theory requires 

 them to produce if they are there. We find no 

 effects : therefore we suppose they are not there. 

 [Applause.] 



2. Pangenetic gemmules might pass everywhere. 

 They can leave the body in the perspiration and the 

 breath. There is no explanation in Mr. Darwin's 

 theory for the presumed fact that they are all col- 

 lected into buds, pollen, or any one similar receptacle. 

 (See letter by Lionel Beale, in "Nature," May 

 11, 1871, p. 26.) 



It is assumed that every cell of every tissue throws 

 off a gemmule in every stage of its development. 

 Now, the gemmules are so small that they may be 

 breathed away; they may be perspired away. Your 

 lily of the valley and your palm tossed in the winds 

 may exude gemmules through all their pores. How 



