74 METHODS IN PLANT HISTOLOGY 



A short history of staining is given in Dr. Conn's book on Biological 

 Stains, in which one can find references to more extensive works on 

 the subject. 



As soon as staining became recognized as a necessary part of histo- 

 logical technique, theories began to appear, some of them suggestive, 

 some instructive, and some only amusing. 



In 1890 Auerbach, a zoologist, published the results of his studies 

 upon spermatozoa and ova. He found that, if preparations containing 

 both spermatozoa and ova were stained with cyanin and erythrosin, 

 the nuclei of the spermatozoa took the cyanin, while the nuclei of ova 

 preferred the erythrosin; hence he proposed the terms "cyanophilous" 

 and "erythrophilous." Auerbach regarded these differences as an in- 

 dication of sexual differences in the cells. 



Rosen (1892) supported this theory, and even went so far as to re- 

 gard the tube nucleus of the pollen grain as female, on account of its 

 erythrophilous staining. In connection with this theory it was sug- 

 gested that the ordinary vegetative nuclei are hermaphrodite, and 

 that in the formation of a female germ nucleus the male elements are 

 extruded, leaving only the erythrophilous female elements; and, simi- 

 larly, in the formation of a male nucleus the female elements are ex- 

 truded, leaving only the cyanophilous male elements. 



As long ago as 1884 Strasburger discovered that with a mixture of 

 fuchsin and iodine green the generative nucleus of a pollen grain stains 

 green, while the tube nucleus stains red. In 1892, in his Verhalten des 

 Pollens, he discussed quite thoroughly the staining reactions of the 

 nuclei. The nuclei of the small prothalhal cells of gymnosperm micro- 

 spores are cyanophilous Hke 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 nutri- 

 tion, 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 de- 

 cidedly 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 pro- 

 nounced, and may even gradually change to the erythrophilous. 



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



