92 BINUCLEATE CELLS 1\ IISSIK CTLTrUES. 



There ha\'e thus been formed two separate and distinct daughter ciUs, in each 

 of which th(> nucleus is becoming gradually reconstituted. As the cell was watched 

 the nuclear areas became clear and the membranes distinct ; nucleoli also appeared, 

 two in each nucleus. Separation of the cells continued, their hyaline borders 

 becoming very active, stretching away into the outlying media and writhing in 

 a sluggish, eel-like manner. Soon the fat globules took up their characteristic 

 arrangement in the cytoplasm, mitochondria appeared, and, in 70, at 8 p. m., 8 

 hours after the observation commenced, we ha^■e to recognize tw(j cells, apparently 

 normal, each with its own centrosome. 



The process of mitosis was identical with that followed manj' times in mono- 

 nucleate cells, except for the variation in the introductory stage, occasioned by the 

 formation of the spireme from two nuclear parts instead of one. The various stages 

 of mitosis, as it is found in the mononucleate cell, are well sliown in tlie series, 

 figures 14, 15, 16, 17, and 18, selected from a fixed j)reparation. 



I have been unable to ascertain whether such spindle formations arising from 

 the fusion of two nuclear portions are possessed of a double number of chromosomes, 

 but the apparent identity of the mitotic i)rocess, after nuclear fusion has taken place, 

 with that occurring in mononucleate cells, does not suggest any material variation 

 in the chromatin arrangement. I am in agreement with Maximow (1908), when 

 he says regarding similar spiremes (p. 95) : " Aus diesen Sjiirenien (>ntstehen immer 

 regelmassige normale Mitosen." 



These cells were not followed farther. The history for the i)eriod of 8 hours, 

 however, shows conclusi\ely that spiremes from these double nuclei may combine 

 to form a single equatorial plate and division may occur l)y the ordinary mitotic 

 process. That such mitosis occurs in all cases it is impossible to state from this 

 isolated observation, but the jiresence of double nuclei (with spin^mes like those 

 shown in figures 22 and 23) here and there in the fixed preparations no doul)t jjoints 

 to the occurrence of such nuclear fusion as a part of the process of mitotic division 

 in the binucleate cell. 



Cases have not been found where one portion only of a bij^artite nucleus was in 

 a condition of mitosis; hence it seems reasonable to conclude that both parts are 

 always in\olved in the process. Tliis much is demanded by our conception of the 

 l)otential unity of the double nucleus, so far as its reproductive capacitj^ is concerned. 



In the case of the cells from which figures 22 and 23 were drawn, it may be 

 argued that these represent telophases in which th(> daughter nucl(>i failed to sei)a- 

 rate. Many mononucleate cells have been followed entirely through the mitotic 

 process, and failure of the daughter nuclei to separate has never been noted. Again, 

 in figure 23, drawn from an iron-hematoxylin i)reparation, there is only a single 

 centriole-pair, not two, as would be the case in a telojihase. 



It might even be suggested that .such daughter nuclei have recombined, as 

 ob.served by Kite and Chambers (_1912); here, however, artificial conditions were 

 existent, since the cells were being forcibh* separated in the Barber moist chamber 

 by mechanical means. Moreover, entire absence of constriction of the cytoplasm, 

 as would occur in the telophase, jwints to the condition we are con.'^idering as repre- 

 senting the prophase. More than this, the fact that the process has been followed 



