42 RICHARD GOLDSCHMIDT. 



the usual way. Nothing is known about the cytology of the 

 occasional males in the parthenogenetic races. It is therefore 

 impossible to tell with which of the possibilities we are here 

 dealing. 



8. Nematodes. The strange type of parthenogenesis described 

 for a Rhabditis by Krueger ('12) and resulting in female off- 

 spring, occurs without a reduction of the chromosomes. Here 

 we have case 2J3. 



9. Echinoderms . (Artificial parthenogenesis.) Tennant'swork 

 makes it pretty certain that the male is heterozygous. Arti- 

 ficial parthenogenesis with reduced chromosome number ought 

 to yield males as in the bee. This has been found to occur in the 

 few recorded specimens. 



10. Amphibia. -(Artificial parthenogenesis.) We do not know 

 which sex is heterozygous in Amphibia. R. Hertwig thinks it is 

 the male. We tried ('n, '13) to show that the experimental 

 results favor the view of female heterozygosis. Moreover we do 

 not know whether parthenogenesis takes place with the haploid 

 or the diploid number of chromosomes. The expectations can 

 therefore fit any of the above enumerated cases. 



I want to emphasize, finally, the fact that our thesis, if ex- 

 pressed in terms of cytology, is nothing but Wilson's old hypo- 

 thesis of the one portion-two portion ^-substance. But our 

 experiments have allowed us to give a physiological meaning to 

 this conception and to bring this cytological conception into 

 harmony with Mendelian formulations. 



OSBORNE ZOOLOGICAL LABORATORY, 



YALE UNIVERSITY, NEW HAVEN, CONN. 



LITERATURE. 

 Artom, C. 



'11 Analise Comparativa della sostanza cromatica, etc. Arch. Zellforsch., 7, 



1911. 

 Baehr, W. B. von 



'07 Ueber die Zahl der Richtungskoerper in parthenogenetisch sich entwickeln- 



den Eiern von Bacillus rossii. Zool. Jahrb. (An.), v. 24. 



'09 Die Oogenese bei einigen viviparen Aphididen, etc. Arch, f . Zellforsch., v. 3. 

 Dohrn, C. A. 



'71 Aus Parthenogonien. Entomol. Ztg. Stettin, 32. 

 Doncaster, L. 



'06 On the Maturation of the Unfertilized Egg and the Fate of the Polar Bodies 

 in Tenthredinidae. Qu. J. Micr. Sc., 49. 



