50 OLIVE SWEZY. 



without any evidences of necrobiosis has been ninety-three days, 

 and in the majority of these cases death has been caused by in- 

 fection with bacteria or molds or other accidents, and, not, 

 apparently, by any lack of vigor in the tissues themselves. This, 

 in general, seems to be true of most of the cultures which appear 

 to be in a thriving condition after the second day or third day, 

 and especially where renewals of the culture medium have been 

 frequent, and precautions have been taken to avoid tearing or 

 otherwise injuring the tissues. However disintegration fre- 

 quently takes place from no apparent cause. 



Egg albumen presents some difficulties when a stained prep- 

 aration from the culture is desired, on account of its avidity for 

 stains. In the first stained preparations made it was impossible 

 to distinguish the outlines of the cells, and the study of the 

 specimen seemed a hopeless task. This difficulty was later over- 

 come by the following methods : the cover glass was inverted and 

 placed on the mouth of a vial containing a quantity of osmic acid. 

 The mouth of the vial was small enough to be completely covered 

 by the cover glass and yet not touch the preparation. After 

 fixing in this manner for ten minutes the cover glass was placed 

 in a stender dish containing distilled water and left for a number 

 of hours. Frequent agitation and changes of the water removes 

 the greater part of the albumen, leaving the tissue adhering to 

 the glass, which may then be put through the alcohols and stained 

 in the usual way. With this method very clear preparations may 

 be obtained. 



Zoological Laboratory, 



University of California, 



Berkeley, Cal., October 13, 1914. 



