1902.] NATURAL SCIEXCES OF PHILADELPHIA. 295 



be given of cells coutaiuiug from a dozen to twenty-five fragments 

 of the nucleus. No explanation of the phenomenon can be given 

 at present further than to say that there are many reasons to regard 

 it as pathological, or " degenerative" in Lowit's sense (see page 

 296). 



I have found the intestine of a young Porcellio, 1.8 mm. in 

 length, which had recently moulted the posterior half (Sec. iii, (4) ), 

 to be literally filled with amitotic division, both longitudinal and 

 transverse, throughout its length (fig. 2, C). ^Eany miclei were 

 in process of division ; those already separated were approximately 

 half the volume of others not yet beginning to constrict. There 

 can be no doubt that the large nuud^er of divisions was correlated 

 with the increase in size of the intestine immediately following the 

 moult. It seems equally plain that two nucleated cells which are 

 larger than adjacent ones, as in fig. 2, A, may represent precocious 

 nuclear divisions, the constriction which will divide the cell being 

 deferred to the next moult, W'hen the luminal end of the cell will 

 be free to cover the new furrow, as well as the old surface, with 

 chitin. 



It is evident that amitosis has been seen in the isopod intestine 

 by a number of observers. Carnoy (10) claims to have seen " the 

 constriction of the nucleus in the epithelium of the intestine of the 

 Crustacea, e. g. , Oniscus asellus, Ligia, A nnadillo asellu.'^, Idotea, 

 Cirolana, etc." He figures amitosis in the testicle cells of the 

 isopod, and says these represent exactly what is to be seen in the 

 nuclei of intestinal cells, so far as the phenomena of division are con- 

 cerned. It is possible, however, that Carnoy, as ^IMc^Iurrich and 

 Schonichen think, may have mistaken distortions of the nucleus for 

 amitosis. Indeed, v. Bambeke (11) refers to one of the figures given 

 by Carnoy as a deformed nucleus. Ziegler and vom Rath (12) say 

 that the " mid-gut " of Oniscus, Porcellio, Cymothoa and Anilocra 

 show amitotic nuclear divisions with special clearness and very 

 abundantly (" besonders deutlich uud recht hiiufig"); but as will 

 be seen imder the subject of the nucleus later, and as was recog- 

 nized by Schonichen, it appears probable that they, too, confused 

 with amitosis certain distortions of the nucleus. Conklin says, 

 speaking of elongated nuclei extending into two cells, " some of 

 these, I am convinced, are amitotic divisions of the nucleus." Since 

 these observations have been called in question by jMcMurrich on the 

 basis of the very frequent misjudgment of irregularly shaped nuclei, 

 it has seemed worth while communicating my own observations. In 

 conclusion, I may say there is no possible doubt that amitosis does 

 actually occur in the growing intestine, nor any doubt that it has 

 here the same significance which Frenzel (13) ascribes to the phe- 

 nomenon in the mid-gut of Astacus and other decapods, namely, a 

 true cell multiplication (" nicht einzig und allein cine Kcrnvermeh- 

 rung, sondernebensowohlaucheine wahreZcllvermehrung," p. o59). 



