DEPARTMENT OF EMBRYOLOGY. 79 



observations of Dr. Lewis. Neutral-red granules and vacuoles accu- 

 mulated in the cytoplasm of the fibroblasts in proportion to the degree 

 of degeneration of the cell. It has been maintained by some that 

 these bodies correspond to food vacuoles. Miss Prigosen rules out 

 any question of phagocytosis or simple intracellular accumulation of 

 dye, and finds the staining reaction of these vacuoles (yellow or brick- 

 red) to be quite different from that exhibited by the food vacuoles 

 (rose tint). 



Another method of producing degeneration vacuoles has been 

 found by Mrs. Margaret R. Lewis. Advantage was taken of the fact 

 that dextrose is an essential part of the medium for tissue culture and 

 that its absence results in a disturbance in the normal metabolism 

 of the cell. Mrs. Lewis was thus able to produce degeneration vacuoles 

 by decreasing the dextrose in the culture medium. In media lacking 

 dextrose the cells showed numerous vacuoles in 24 to 48 hours; in 

 media containing 0.25 per cent dextrose, vacuolization, degeneration, 

 and death of the cells were retarded several days; while in media 

 containing from 0.5 to 1 per cent dextrose the cells continued in an 

 apparently healthy condition for as long as two or three weeks without 

 the appearance of vacuoles. 



From a study of the effects of egg white introduced into the medium 

 of a culture of connective tissue, Mrs. Lewis has been able to dif- 

 ferentiate a type of cell granule which she terms the "al" granule, 

 mention of which was made in a preceding paragraph. These granules 

 are large, rounded, somewhat refractive bodies formed within the 

 cytoplasm of connective-tissue cells. When stained with eosin they 

 resemble the colloid or hyaline droplets seen in renal epithelium under 

 pathological conditions, and when stained with iron hematoxylin 

 the cells containing them resemble cells undergoing active secretion. 

 The al granules, both in living and fixed material, are easily dis- 

 tinguishable from neutral-red granules, with which they may exist 

 side by side in degenerating cultures. They differ also from pigment 

 granules and certain secretion granules, in that they are less frequently 

 found collected around the centrosphere. The processes of the cells 

 are always free from these al granules. Cells were found to divide by 

 mitosis even when full of the granules, whereas mitotic division is 

 rarely seen in the presence of degeneration vacuoles. There is some 

 variation in their size, but in most cases they are much larger than 

 either mitochondrial bodies or neutral-red granules. They are not 

 readily stained by vital dyes, although they show a slight reaction to 

 neutral red. In fixed preparations stained with iron hematoxylin 

 they appear in various shades, from dense black to gray. When em- 

 bryonic connective tissue was placed in egg albumin, the cells grew out 

 in the medium much as in normal cultures, and at the end of 16 hours 

 they contained many of the al granules, the maximum number being 



