392 



SCIENCE. 



[N. S. Vol. XIX. No. 479. 



in does this case differ from the other two? 



May we not reasonably exercise some 

 ' critical caution ' before with Wheeler we 

 conclude it probable ' that worker ants can . 

 really produce other workers or even queens 

 parthenogenetieally ' ? But suppose they can; 

 wherein lies the ' ominous import ' which such 

 a possibility has for ' current views on sex 

 determination ' ? For myself, I do not see 

 that the case of the ant would then present 

 any new problems not found either in the 

 case of Nematus, or in the silk-moth, or in 

 DapTinia, to any theory of sex determination 

 ever conceived or conceivable. Should it be 

 shown that the unfertilized eggs of the ant 

 may develop either into males or into females 

 (at present we have no evidence whatever that 

 such is the case), then it would be in order 

 to inquire whether all such eggs undergo two 

 maturation divisions, as do the eggs of the 

 bee, or whether, as in the Eotifera and Crus- 

 tacea, male parthenogenetie eggs undergo two 

 maturation divisions, whereas female par- 

 thenogenetie eggs undergo only one. 



W. E. Castle. 



Zoological Labokatoey, 

 Haevaed University, 

 January 25, 1904. 



SPECIAL ARTICLES. 



AMITOSIS m THE EGG FOLLICLE CELLS OP INSECTS. 



Professor Conklin's interesting account of 

 the amitotically dividing egg follicle cells of 

 the common crickets {Gryllus -pennsylv aniens, 

 abhreviatus and domesticus) in the American 

 Naturalist for October, 1903, recalls attention 

 to a condition and phenomenon in animal 

 cytology all too little known. Despite the 

 rarity of amitotic cell division elsewhere 

 among animals, and the interest and signifi- 

 cance of the phenomenon, the opportunity 

 offered for its study in the egg follicle cells of 

 insects has been taken little advantage of. 

 We know simply that amitotic division occurs 

 in some of these cells in certain insects. How 

 consistently through the insect class ; whether 

 identical or varying in character among the 

 different insect species in which it occurs ; and 

 finally and most importantly, how far back 

 in the lineage (ancestry) of the cells them- 



selves the phenomenon persists; in other 

 words, at what time the amitotic division ap- 

 pears in the history of cells which must be 

 derived from cells with mitosis; all these in- 

 teresting questions remain to be answered. 

 Professor Conklin finds that only in the 

 follicle of the lowest egg-chamber of each 

 ovarial tube of Gryllus are all the cells ami- 



FlG. 1. Egg follicle cells of Hydrophilus sp. 

 amitotic division. 



showing 



totically dividing. In the upper chambers or 

 sections of the tubes the division of the cells 

 is always (as far as observed) mitotic; in the 

 lowest chamber, on the contrary, always ami- 

 totic. 



The obvious conclusion, in the light of our 

 knowledge of the fate of the follicular cells 

 of the lowest chamber — they secrete here the 

 chorion of the egg and then give up the ghost 

 — that the amitosis is a concomitant with 

 senescence and decay, is probably indisputable. 

 But it is a fact that in not all of the few 

 insects in which this amitosis has been stud- 

 ied is it limited to the follicle cells of the last 

 egg chamber. 



Certain differences exist in the character 

 of the amitosis of the egg follicle cells of 

 Gryllus (as described by Professor Conklin) 



