General Remarks on Staining 67 



stains green, while the tube nucleus stains red. In 1892 1 he dis- 

 cussed quite thoroughly the staining reactions of the nuclei. The 

 nuclei of the small prothallial cells of gymnosperm microspores are 

 cyanophilous like the male generative nuclei. The nuclei of a nucellus 

 surrounding an embryo-sac are also cyanophilous, while the nuclei of 

 structures within the sac are erythrophilous. His conclusion is that 

 the cyanophilous condition in both cases is due to poor nutrition, 

 while the erythrophilous condition is due to abundant nutrition. A 

 further fact in support of the theory is that the nuclei of the adventi- 

 tious embryos which come from the nucellus of Funkia ovata are 

 decidedly erythrophilous, while the nuclei of the nucellus to which 

 they owe their food-supply are cyanophilous. 



In division stages nuclei are cyanophilous, but from anaphase 

 to resting stage the cyanophilous condition becomes less and less 

 pronounced, and may even gradually change to the erythrophilous. 



An additional fact in favor of this theory is that in Ephedra the 

 tube nucleus, which has very little cytoplasm about it, is cyanophilous. 

 Strasburger claimed that there is no essential difference between 

 male and female generative nuclei, and subsequent observation soon 

 showed that within the oospore the sex nuclei rapidly become alike 

 in their reaction to stains. 



Malfatti (1891) and Lilienfeld (1892-93) claim that these reac- 

 tions are dependent upon the amount of nucleic acid present in the 

 structures. During mitosis the chromosomes consist of nearly 

 pure nucleic acid and are intensely cyanophilous, but the proto- 

 plasm, which has little or no nucleic acid, is erythrophilous. There 

 is a gradual transition from the cyanophilous condition to the ery- 

 throphilous, and vice versa, the acid structures taking basic stains 

 and basic structures the acid stains. 



The terms " erythrophilous'' and " cyanophilous'' soon became 

 obsolete, and many claimed the affinity is for basic and acid dyes, 

 rather than for blue or red colors. That the terms were misnomers 

 became evident when a combination like safranin (basic) and acid 

 green (acid) was used, for the cyanophilous structures stained red, 

 and the erythrophilous green. 



l Verhalten des Pollens. 



