294 RUTH STOCKING LYNCH 



creasingly more fat (figs. 2, 7, 12, 14, 17, 18), and the cells of 

 sixteen day embryos usually contained numerous large globules 

 (fig. 16). There was no correlation between the amount of fat 

 and the age of the culture. The number or size of the fat glob- 

 ules in the cells did not change as the culture aged. 



Degeneration 



In general, degeneration of the liver cells took place either by 

 vacuolization or by bleb formation. These two processes never 

 occurred together in the same culture: a culture which degener- 

 ated by bleb formation never showed any vacuolization of its cells 

 (fig. 18); on the other hand, the cells of a culture in which 

 vacuoles were found never showed any tendency to form blebs 

 (figs. 2, 10, 11, 17, 22, 23, 25). 



In two cultures vacuoles were observed on the first day after 

 planting; in one case the first vacuoles appeared on the eighth 

 day after planting; in most cases they appeared on the third day. 

 The first vacuoles were single and small, approaching the nucleo- 

 lus in size, and were present in only a few cells of the culture. 

 Vacuolization in these cultures was progressive in extent as well 

 as in degree, not all the cells becoming vacuolated at once. 



Most of the vacuoles observed were smoothly spherical in 

 form and did not change in shape or position. Some, however, 

 were very irregular and constantly changing form, extending 

 first in one place and then in another and consequently shifting 

 about considerably in the cell. In some cases the vacuoles 

 merely bulged out in various places (figs, 2, 11); in others defi- 

 nite processes were thrown out and withdrawn (fig. 9b). Some- 

 times these processes were very long and slender, forming vacuo- 

 lar channels similar to those described by Lewis and Lewis'* and 

 W. H. Lewis.3 



The vacuoles and their processes stained with neutral red, 

 varying in color from a very light pink to a red, according to the 

 concentration of the solution. No staining with any of the 

 trypan-blue solutions used was observed. 



* Lewis, M. R. and W. H. 1915. Mitochondria and other cytoplasmic struc- 

 tures in tissue cultures. Am. Jour. Anat., vol. XVII. 



