96 Methods in Plant Histology 



per cent glycerin. The brown or black spores of fungi are readily 

 mounted in this way. 



The method is very useful when one finds a single specimen 

 of Pediastrum, or any small form which would be lost in the more 

 complicated processes. Place a large drop of 10 per cent glycerin 

 on a slide; with a pipette, transfer the object to the drop, and allow 

 the glycerin to concentrate. Then add a cover and seal the mount. 



GLYCERIN JELLY 



Glycerin jelly is useful for objects which are too large to mount 

 in glycerin without making cells. With objects as large as Volvox 

 or branches of Cham, the glycerin is likely to ooze out beyond the 

 cover, making it difficult or impossible to seal the mount. Such 

 objects may be mounted in glycerin jelly. The material should be 

 put into 10 per cent glycerin, which should be allowed to concentrate 

 until it is as thick as pure glycerin. The bottle containing the 

 glycerin jelly is then put into warm water until the jelly melts. 

 No more heat should be applied than is really necessary. Place a 

 drop of the melted jelly on a warm slide, and place on it the material 

 to be mounted. Add a cover, and allow the mount to cool. In 

 cold weather, a glycerin-jelly mount is safe without sealing, but in 

 summer the jelly may melt. It is better to seal all glycerin-jelly 

 mounts. 



It is a common practice to put a small piece of the glycerin jelly 

 on the slide and heat the slide until the jelly melts. The only objec- 

 tion is that one may ruin his material by putting it into the drop 

 while it is too hot. 



