164 BOTANICAL MICROTECHNIQUE. 



mycelium of the Peronosporacecz, where it partly incrusts the 

 cellulose walls and partly occurs in more or less pure condi- 

 tion in the interiors of the hyphae and of the haustoria (cf. 

 Mangin III). [The same author has also shown (IX) the 

 presence of this substance in various cell-walls of Phanero- 

 gams which are incrusted with carbonate of lime, especially 

 those of the cystoliths of the Urticales and of the calca- 

 reous hairs and pericarps of several Borraginacece. In the 

 achenes of Lithospermum, Cynoglossum, etc., where it occurs, 

 without a deposit of lime, its occurrence seems to be related 

 to the disappearance of the cell-contents and the gradual 

 destruction of the parenchyma. He has also observed it in 

 the walls of cells bordering tissues which have become 

 suberized in consequence of injuries.] 



This author calls this substance callose, a term which 

 deserves preference, since the word "callus" is used, as is 

 well known, in quite another sense. 



288a. Callose gives the following reactions, according to 

 Mangin (II) : It is insoluble in water, alcohol, and cupram- 

 monia, in the latter even after previous treatment with 

 acids. But it is readily soluble in a cold \% solution of 

 caustic soda or potash, and is also soluble in the cold in 

 concentrated sulpJinric acid, as well as in concentrated solu- 

 tions of calcium chloride and stannic chloride. Cold solu- 

 tions of alkaline carbonates and of ammonia make it swell 

 and give it a gelatinous consistency, but without dissolv- 

 ing it. 



Callose also differs from cellulose in its behavior with 

 various coloring matters. Mangin gives (V) a number of 

 azo-colors which deeply stain cellulose in a neutral or feebly 

 acid solution, but leave callose uncolored ; they are espe- 

 cially orseillin BB, azorubin, naphtol black, and the croceins. 

 On the other hand, callose is distinguished by its strong- 

 staining capacity with corallin and aniline blue and certain 

 dyes belonging to the benzidines and tolidines. 



289. Corallin or rosolic acid is best dissolved in a 4$ or 

 concentrated aqueous solution of soda (Na 2 CO 3 ). The sec- 

 tions are placed for a short time in this solution and then 



