No. 578] 



CYCLES AND RHYTHMS 



"Woodruff and Erdmann limit the application of the 

 term endomixis to the process of reorganization without 

 conjugation: 



We therefore have employed a new term "endomixis" for the re- 

 organization process in Paramecium, in preference to parthenogenesis 

 which Hertwig applied when lie incident ;illy noted some isolated stages 

 of the nuclear phenomena which we have elucidated. 8 

 A new name can not alter the significance of a process or 

 phenomenon. Parthenogenesis, in its broad sense, is the 

 development of an individual from an egg without fertili- 

 zation. In the same sense that a Paramecium ex-conju- 

 gant develops into a new individual, so does a Parame- 

 cium after this process termed endomixis. Woodruff and 

 Erdmann say: 



In parthenogenesis there is a chromatin reduction which occurs and 

 is compensated for either in the egg itself or in some later period of the 

 life cycle of the race. 9 



The authors are not very happy in selecting this feature 

 as distinguishing parthenogenesis from asexual endo- 

 mixis, for in most cases of recognized parthenogenesis 

 in metazoa chromatin reduction plays no part; for exam- 

 ple, the majority of parthenogenetic 'eggs give off only 

 one polar body, thus retaining in the egg the diploid num- 

 ber of chromosomes ; others, notably the aphids and phyl- 

 loxerans, do not undergo synapsis or chromatin reduction ; 

 some others it is true, give off both polar bodies and develop 

 with the haploid number of chromosomes as is the case 

 in bees (males), and in artificial parthenogenesis. As to 

 the significance of parthenogenesis neither polar body 

 formation nor chromosome reduction furnishes the key, 

 for in many cases the eggs are predestined to partheno- 

 genetic development long before the polar body nuclei 

 are formed. 



In regard to the reducing divisions of the chromosomes 

 in Paramecium we know very little. Evidence has been 

 adduced to indicate that the chromosomes are divided 



•Ibid., p. 493. 



Ibid., p. 492. 



