Varietäten, Descendenz, Hybriden. 519 



gens as separate entities or corpuscles of any sort we may think 

 of them as parts of the ancestral lines that form the network of 

 descent of the species. 



The assumption that characters are pre-existent in the proto- 

 plasm of germ cells as discrete particles or independent units of 

 any sort is not justified by Observation or by logical necessity. 

 Equally convenient and more truly biological methods of thinking 

 about the problems of heredity can be developed by recognizing the 

 relation of heredity to the network of descent of the species. This 

 conception allows characters to be thought of as representing lines 

 of descent instead of as discrete particles in the protoplasm. 



M. J. Sirks (Haarlem). 



Cook, O. F., Sexual inequality in hemp. (Journ. of Heredity, 

 V. p. 203-206. 1914.) 



A remarkable case of sexual inequality is described bj^ the 

 writer in a plot of hemp, grown in Virginia and recognized as 

 the so-called Russian or Manchurian hemp, probably the same as 

 that described by Pallas as Cannabis erratica, though it is not 

 usually considered as a species distinct from the ordinary C. sativa. 

 All of the male plants were very slender and spindling, and the 

 foliage was of a pale yellowish green color, in strong contrast with 

 the deep blackish green of the female plants. In addition to their 

 more robust form, the female plants were often a foot taller than 

 adjacent males, the largest of the female plants attaining about 

 three feet. Many of the male plants had already died at the time 

 the photographs, illustrating the paper, were taken, August 13, 

 and the others were evidently to follow shortly. But all of the 

 female plants were still fresh and vigorous, and were growing and 

 flowering under conditions that where bringing the male plants to 

 an early death. 



Other varieties of hemp, not grown for seedproduction, bot for 

 fibre or drug purposes do not show such a striking inequality of 

 the sexes. Though the male plants die somewhat in advance of the 

 females, they attain nearly the same stature and live through most 

 of the season. 



The writer has not determined the extent to which the presence 

 or the competition of the female plants ma}'' be responsible for the 

 early of the death of the male plants, neither does he indicate the 

 causes of this. Only the desirability that the males die early and 

 the advantages of this early death are discussed. "Under extreme 

 conditions short-lived male plants would be likely to leave larger 

 progenies, for the female plants that stood next to short-lived males 

 would be able to ripen more seed. The natural result of such Va- 

 riation and selection would be the development of a plant with 

 short-lived, ephemeral males corresponding to drone bees and similar 

 specializations of the sexes among insects and other invertebrate 

 animals". "But the advantage of having the males die earlier would 

 not of itself cause them to die. Some other specialization or inten- 

 sification of the sexual differences must have arisen". 



M. J. Sirks (Haarlem). 



Cook, O. F., The existence of species. (Journ. of Heredity. 

 V. p. 155—158. 1914.) 

 The following quotations from this paper may be given here 

 as characteristic for the author's point of view; 



