BINUCLEATE CELLS IN TISSUE CULTURES. 79 



sphere situated in the concavitj' (fig. 24c). This concave side then appears indis- 

 tinctly marked out in the living culture, the close proximity of the centrosphere 

 and mitochondria obscuring the nuclear outline. Its relation to the parts of the 

 double nucleus has been noted. 



I have not observed the centrosome (centriole) in the living cell, but when 

 stained with iron hematoxylin this body appears usually as two minute dark 

 granules, lying close together (fig. 7). The centi'osphere takes a slightly darker 

 stain than the area surrounding it, and thus appears to be a somewhat more concen- 

 trated area of the protoplasm. From this area mitochondria radiate, as seen in 

 figure 8. In the living condition the centrosphere shows an indefinite, irregular, 

 apparently serrated edge, the toothlike processes of which undergo a curious con- 

 stant, slow, almost imperceptible indrawing and outpushing. The mitochondria 

 seem to be intimatelj^ connected with this body, as observed by Lewis and Lewis 

 (1915, p. 349), but they differ from it in their reaction to janus green and to certain 

 methods of staining in the fixed condition, such as iron hematoxylin. 



Mitochondria in tissue cultures have been described at length by Lewis and 

 Lewis (1914, 1915). Their curious movement, mentioned by these authors, is 

 plainly evident. The special relation of these bodies to the binucleate cell is their 

 position between the nuclear portions, as in figures 8 and 9, unless, as in figure 7, the 

 parts of the nucleus are too close together to permit of this. The relationship of the 

 mitochondria and adjacent centrosphere to the portions of the double nucleus is 

 similar to that of the Netzapparat of Deineka (1912, figs. 2 and 12) under similar 

 conditions. 



Fat, though not so abundant as in plasma-grown cultures, nevertheless occurs 

 as fine globules which tend to crowd together at the nuclear poles (fig. 32) and 

 often become arranged in rows between the mitochondria. 



The other details of the binucleate cell are very similar to those found in the 

 mononucleate. 



Occasionally cells are found which contain three or more distinct nuclei (fig. 16) 

 and the evidence seems to indicate that the binucleate cell is the first stage in the 

 formation of the giant cell; this stage, however, is seldom passed, for giant cells are 

 comparatively rare. Such multinucleate cells are quite different from the foreign- 

 body giant cells of Lambert (1912 o and b), which have been shown b}^ him to arise 

 by fusion of i^reviously separate wandering cells. 



Binucleate cells, and the intermediate stages leading up to them, have long 

 been known in embryonic tissue. Child (1907c) shows several such from chick 

 embryos in his figure 12. IVIaximow (1908) describes and figures double nucleated 

 cells, similar to those found in tissue cultures, in mesenchj-me of embryo rabbits of 

 11^ to 13§ days, and he has found araitosis also in the guinea pig in the same region 

 and stage. Patterson (1908) shows illustrations of cells of the same type in develop- 

 ing pigeon's eggs, and such cells have been described by many others. Thus it is 

 certain that, since the paired nucleus occurring in the tissue-culture cell is similar to 

 that found in the cells of embryonic tissue, it can not be considered as an abnor- 

 mality due to its artificial mode of life. 



