540 



Journal of Applied Microscopy. 



To illustrate the reserve material in seeds, one-half of the seed to be pre- 

 served is taken and placed in a solution of iodine. This, as is well known, will 

 color the starch a deep blue color. Inasmuch as iodine is not a permanent 

 stain, the color will soon fade when the substance is placed in formalin, but if a 

 crystal of iodine is placed in the solution, the reaction can be retained indefi- 

 nitely ; or if a slight amount of nitric acid is placed in the formalin, the iodine 

 color can be retained quite well for a long time. We have sections of seeds 

 which have been in nitric acid formalin for three or more years, that completely 

 retain their iodine reaction. 



After having made extensive trials of both formalin and alcohol as media for 

 preserving specimens, we are convinced that formalin is greatly superior to 



Figure III. 

 Puff-ball. Mycelium development. 



Figure IV. 



Leaf-spit of cherry mounted in 



formalin glycerine gelatin. 



alcohol. Formalin solution gives a clean white color to tissues, whereas, alcohol 

 always turns them to a dirty brown. 



We found by repeated trials that it was impossible to preserve the delicate 

 roots of the plants with alcohol and have them retain their natural color. More- 

 over, it was difficult, on account of the more volatile nature of alcohol, to keep 

 specimens from shrivelling up when left out of the solutions for a few moments, 

 as is necessary in mounting them up. With formalin, however, no such difficulty 

 arises and the specimens may be left some time in exposure to the air without 

 detriment. G. E. Stone. 



Botanical Laboratory, Massachusetts Agricultural College. 



