438 Journal of Applied Microscopy. 



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 adventitious embr}^'OS 

 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, cytoplasm is taken into the nucleus, and the cyanophilous condition 

 gradually changes 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 claims 

 that there is no essential difference between male and female generative nuclei, 

 and subsequent observation has shown that within the oospore the sex nuclei 

 are alike in their reaction to stains. 



Malfatti (1891) and Lilienfeld (1S92-3) claim that these reactions 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 protoplasm, which has little or no nucleic acid, is ery- 

 throphilous. There is a gradual transition from the cyanophilous condition to 

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

 basic structures the acid stains. 



The terms erythrophilous and cyanophilous are falling into disuse since the 

 affinity is for basic and acid dyes, rather than for blue or red colors. That the 

 terms are misnomers becomes evident when a combination like safranin (basic) 

 and acid green (acid) is used, for the cyanophilous structures stain red, and the 

 erythrophilous green. 



Probably but few investigators who have attained any proficiency in micro- 

 technique have not asked themselves how much dependence can be placed upon 

 staining reactions as a means of analysis. Do staining reactions enable us to 

 determine the chemical composition of a structure ? If two structures stain 

 alike with Delafield's hajmatoxylin, does this mean that they have the same 

 chemical composition, or, if on the other hand they stain differently, must they 

 necessarily be different in their chemical composition ? Delafield's haematoxylin, 

 when carefully used, gives a rich purple color, but a careful examination will 

 often show that in the same preparation some structures §tain purple, while 

 others stain red. Does this mean that the purple and red structures must have 

 a different chemical composition ? Many people believe that structures which 

 stain differently with a given stain must be chemically different, but they readily 

 agree that structures which stain alike are not necessarily similar in chemical 

 composition. Chromosomes of dividing nuclei and lignified cell walls stain alike 

 with safranin ; chromosomes and cellulose cell walls stain much alike with 

 Delafield's ha;matoxylin, but every one recognizes that the chromosome is very 



