246 M. R. LEWIS. 



wine color was present in the same regions as in normal cultures, 

 but never greater in amount and sometimes less than in the 

 normal control preparations. Even after a number of days the 

 starch did not become changed into glycogen as, for instance, 

 one 8-day-old culture in 0.75 per cent, starch solution, exposed 

 to iodine, exhibited cells in which there were a few vacuoles 

 some of which contained blue granules. The vacuoles were pale 

 blue or lilac but never port-wine color. 



INFLUENCE OF DEXTROSE IN THE MEDIUM UPON THE 

 AMOUNT OF GLYCOGEN IN THE CELLS. 



Cultures were prepared in a medium free from dextrose in 

 order to ascertain whether the lack of dextrose would prevent 

 the appearance of glycogen in the cytoplasm of the cells. The 

 results from twenty such cultures show that, while the amount 

 of glycogen could be decreased by the lack of dextrose in the 

 medium, its presence could not be entirely inhibited. Some of 

 these cultures (48 to 72 hours) exhibited only a slight trace, if 

 any, of the port-wine color when exposed to iodine. On the 

 other hand, a few did contain decided evidences of a small 

 quantity of this substance. 



Explants into media containing 0.5 per cent., I per cent, and 

 2 per cent, dextrose, made at the same time as those without 

 dextrose, showed a decided increase in the quantity of glycogen 

 up to a certain point. In no instance did all of the cells of a 

 culture exhibit the port-wine color. Neither did any one cell 

 become greatly filled with this substance. Of all the cultures, 

 those grown in a solution containing 2 per cent, dextrose exhibited 

 the most marked amount of the port-wine-colored material; 

 that is, more cells contained this substance, practically all of 

 the fan-shaped processes had regions which were stained port- 

 wine color, and the color was deeper in tone and did not fade as 

 rapidly as in the normal cultures. Saliva placed upon cultures 

 in 2 per cent, dextrose prevented the appearance of the port- 

 wine color, just as it did in the normal cultures. In these experi- 

 ments with different amounts of dextrose it was impossible to 

 predict whether a given cell would show the port-wine color in 



