1896.] MICROSCOPICAL JOURNAL 381 



cesB do verj^ well indeed. Phseophyceae, almost without 

 exception, are rendered brittle in a short time, but while 

 this renders them troublesome to manage, yet specimens 

 prepared in this way and soaked out in water are excel- 

 lent for study hy crushing methods. It is the intercel- 

 lular substance that is rendered brittle and such forms as 

 species of Leathesia, Mesogloia, Laminaria, etc., when 

 crushed, spread out and show the cell structure and cell 

 arrangement in a very satisfactory fashion. The color is 

 not retained perfectly, but is ordinarily retained more 

 than by any other of "the media we have tried. 



The Chlorophycea? lose all of their green, or nearly 

 all. The Cyanophycese and Rhodophycese often retain 

 considerable (especially if kept away from the light), 

 generally at least enough to assist materially in the ex- 

 amination of the chromatophores, while the PhseophyceaB 

 lose very little of their intensity. Specimens preserved 

 in chrome alum must be kept in glass-stoppered jars, 

 carefully closed, as the solution is liable to become in- 

 vaded by various molds, A little finely divided camphor- 

 gum at the top will prevent this, as will also a small 

 quantity of formalin. Chrome alum solution has a cer- 

 tain corrosive action upon metals; so that metal tops to 

 the preserving jars should be avoided, and specimens to 

 be sectioned free-hand or with the freezing microtome 

 methods, should have at leastthe greater part of the alum 

 removed by washing. 



One per cent chrome alum is also an excellent preserv- 

 ing fluid for use with fungi of the various groups, for 

 the mosses, for ferns and for flowering plants, better in 

 all cases than the strong alcohol commonly, used, but 

 probably not superior to the various percentages of for- 

 malin, except in the case of gelatinous forms. Spirogyra 

 cells keep well in 1 per cent chrome alum, the chroma- 

 tophores, pyrenoids, nuclei and protoplasmic sac and 

 threads showing very well indeed. Specimens kej)t in a 



