322 THE DOCTRINE OF DESCENT. 



1872), and Contributions to the Theory of Natural Selection (2nd 

 ed.: 1871). 



5^ " The hypothesis of Pangenesis, as applied to the several great 

 classes of facts just discussed, no doubt is extremely complex, but 

 so assuredly are the facts. The assumptions, however, on which 

 the hypothesis rests cannot be considered as complex in any 

 extreme degree ; namely, that all organic units, besides having the 

 power, as is generally admitted, of growing by self-division, throw 

 off free and minute atoms of their contents, that is, gemmules. 

 These multiply, and aggregate themselves into buds and the sexual 

 elements ; their development depends on their union with other 

 nascent cells, or units, and they are capable of transmission in a 

 dormant state to successive generations. 



" In a highly organised and complex animal, the gemmules thrown 

 off from each different cell, or unit, throughout the body must be 

 inconceivably numerous and minute. Each unit of each part, as it 

 changes during development — and we know that some insects 

 undergo, at least, twenty metamorphoses — must throw off its 

 gemmules. All organic beings, moreover, include many dormant 

 gemmules derived from their grand-parents and more remote pro- 

 genitors. These almost infinitely numerous and minute gemmules 

 must be included in each bud, ovule, spermaozoon, and pollen grain. 

 Such an admission will be declared impossible, but, as previously 

 remarked, number and size are only relative difficulties, and the 

 eggs or seeds produced by certain animals or plants are so 

 numerous that they cannot be grasped by the intellect." Darwin, 

 Variations of Animals and Plants, II. 526. 



^7 A. Rollet, Ueber die Erscheinungsformen des Lebens und den 

 beharrlichen Zeugen ihres Zusammenhanges. Almanach der kais. 

 Akademie der Wissenschaften (Wien, 1872). 



5** Darwin, Variations of Animals and Plants, I. 200. 



59 V. Graber, Ueber den Tonapparat der Locustiden, ein Beitrag 

 zum Darwinismus. Zeitschrift fur wissenschaftliche Zoologie. 



Vol. 22. 



^" Hermann v. Nathusius, Vorstudien fiir Geschichte und Zucht 

 der Hausthiere zunachst am Schweineschadel, 1864. 



" lb., p. 108. 



«- Descent of Man, I. 412. 



