PROTOPLASM. 83 



tion of protoplasm in the asci of ascomycetes [con- 

 taining much glycogen], assumes a deep reddish- 

 brown or violet-brown color with even a very dilute 

 solution of iodine. 



The preparation of the nucleus, which has been 

 so zealously studied of late, has formed the subject 

 of many contributions. 1 Acetic acid, alcohol, and 

 perosmic acid differentiate it sharply, and are 

 therefore used to render it evident. Coloring 

 matters are taken up and condensed by the nu- 

 cleus. The effect of haematoxylin, aniline green, 

 Grenadier's alum-carmine, ammonia-carmine, and 

 picro-carmine, is to color the nucleus deeper than 

 the rest of the protoplasm in the cell. Iodine acts 

 in exactly the same manner. Successive treat- 

 ment with alcohol, picro-carmine, and glacial acetic 

 acid is recommended by Maupas. 



Among the various substances of the protein 

 group, nuclein has been especially studied by 

 Zacharias 2 and others. To detect it, immerse the 

 preparation for an hour in a mixture of one volume 

 of a ten per cent, solution of the yellow ferro- 

 cyanide of potassium in distilled water, and two 

 volumes of acetic acid, prepared by diluting the 

 glacial acid with an equal bulk of water. Wash 

 the sections in sixty per cent, alcohol. The 



1 Strasburger, Hanstein, Ranvier, Treub, Schmitz, and others have 

 done much in this direction. Cf. further. Treub : Actes du Congres In- 

 ternational des Botanistes, etc., a Amsterdam en 1877, Leide, 1879, p. 146. 

 Maupas : Comptes rendus, July 1879, Vol. LXXX VIII., p. 250. 



2 Zacharias: Bot. Zeitung, 1881, p. 169; 1883, p. 209. 



