8. Abstammungslehre. 247 



8. Abstammungslehre. 



(Siehe auch Nr. 613, 614, 634, 643, 653.) 



683) Harris, J. A., The biometric proof of the pure line theory. 



(Amer. Naturalist 45. p. 346—363. 1911.) 

 This paper is a criticism of Johannsen's pure liae theory from the 

 biometric stand point. Tbe genotype conception is analyzed into three pro- 

 positions: (1) Most species or varieties are composed of many minor forms, 

 (2) these genotypes or biotypes are often separated by exceedingly minute 

 differences, (3) these genotypes are rigid hereditary units; by mutation we 

 may pass from one to the other, but selection within the genotype can effect 

 no change. Of these propositions the main one is tbat selection is ineffective 

 within the pure line or genotype, and it is this Statement which is criticized 

 as unproved. The point is made, that characters which are not inherited at 

 all can not taken to prove that selection in general is ineffective, and such 

 work as that of Pearl and Surface on the increase of egg-laying capacity 

 in fowls can not be interpreted as favoring the genotype theory of heredity. 

 Emphasis is laid upon the fact that no Single character can undergo unlimited 

 improvement, and that selection cannot carry a character beyond the Optimum 

 for maintenance and reproduction of the organism. Various failures of selec- 

 tion are accounted for in this way. Whenever selection is effective the results 

 are charged to the fact that the material was impure, but when selection 

 produces no result this is credited as a confirmation of the genotype theory. 

 It remains to be seen in how for the rigidity of genotypes will be borne 

 out by subsequent work. Gates (St. Louis). 



684) Steche, 0. (Zool. Inst. Leipzig), Die Färbung von Dixippus 

 morosus. 



(Zoolog. Anzeiger 37,2. p. 60—61. 1911.) 



Steche teilt eine Reihe biologischer Beobachtungen mit, die er bei der 

 Zucht einer Stabheuschrecke (Dixippus morosus) gemacht hat. Die Färbung 

 dieser Tiere ist während des individuellen Lebens nicht konstant. Abgesehen 

 von den Farbenänderungen während des Wachstums verschwindet die grüne 

 Farbe nach Erreichung der Geschlechtsreife in fast allen Fällen. Niedrige 

 Temperaturen und reichliche Versorgung mit frischem Futter (Rosenblätter) 

 begünstigen die Grünfärbung. Eine deutliche Erblichkeit bestimmter Fär- 

 bungsvarietäten konnte der Verf. nicht feststellen. F. Pax (Breslau). 



685) Kofoid, C. A. (Univ. of California), A Revision of the Genus 

 Ceratocorys, based on Skeletal Morphology. 



(Univ. of California Pub. in Zoölogy 6,8. p. 177—189. 1910.) 

 Superficial resemblance to other genera in form and organs of flotation 

 has hitherto hidden the true affinities of Ceratocorys, which rest upon ske- 

 letal morphology. Generic characters and a key to species are given; also a 

 füll description of the five species, — Ceratocorys horrida, C. armatum, 

 C. magna, C. bipes and C. jourdani. Stevens (Bryn Mawr). 



686) Grese, N. (Zool. Museum Moskau), Über eine blinde Nemastoma- 

 art aus einer Höhle in der Krim (Nemastoma caecum nov. sp.). 



(Zoolog. Anzeiger 37,5. p. 108. 2 Abb. 1911.) 

 Beschreibung einer neuen Nemastomaart, die in einer Stalaktitenhöhle 

 der Krim in der Umgebung des Dorfes Skelja gesammelt worden ist. Die 



