382 THE AMERICAN MONTHLY [Nov. 



cork-stoppered bottle in chrome alum showed a very dis- 

 tinct dark steel-blue stain afFectinp: the nucleolus most, 

 the nucleus and the chromatophores; and this remained 

 after washing in water, dehydrating, and mounting in 

 Canada balsam. 



With chrome alum, ais well as all other preserving 

 media, a fairly large proportion of fluid should be used. 



Formalin. — Formalin, formalose, or 40 per cent for 

 maldehyde, according to the trade name, has in the last 

 two years become very popular with both zoologists and 

 botanists. It is not necessary for us to go into the lit- 

 erature, but we have found that the 1 to 2 per cent solu- 

 tion of the formalin (1 to 2cc formalin in 99 to 98cc distilled 

 water or sea water) makes a solution sufficiently powerful 

 to kill, fix, and preserve any ordinary vegetable tissue. 

 While the color fades more rapidly than with chrome 

 alum, the cell contents are preserved equally well. For 

 Phseophycese, a 2 per cent formalin solution is the very 

 best fluid which we have tried. CyanophycesB preserve 

 their structure but not the gelatinous matrix so well, since 

 this is liable to shrink under the influence of formalin. 

 Delicate Rhodophycese, such as Griffithsia, Callithamnion 

 Dasya, etc., keep their full form better than in any other 

 fluid. Chlorophycese do equally well. Formalin solu- 

 tions containing organic materials become acid after a 

 short time and this may tend to alter the cell-contents or 

 the intercellular substance slightly, but in preparations 

 kept for nearly two years this is not sufficiently marked 

 to be especially noticeable. Formalin in the same per- 

 centages works excellently for fungi and the higher 

 plants. Toadstools are preserved in their natural shapes 

 and in more or less of their natural colors according to 

 the species. 



Camphor water. — Camphor-gum is sparingly soluble in 

 water, but the solution is very prejudicial to the life of 

 micro-organisms. Camphorated water is very useful 



