SPECIAL METHODS. 19! 



b. The Constituents of the Resting Nucleus. 



335. If we examine more closely the various constituents of 

 the nucleus, the nucleohis presents the part which stains most 

 deeply with most staining methods. In many objects, after 

 the use of the above-described methods and very thorough 

 washing, only the nucleoli appear very deeply stained in the 

 resting nuclei. On the other hand, the so-called chromatin 

 spheres of the nuclear framework are distinguished by 

 marked staining power, and great differences in this respect 

 occur in different plants and tissues, as well as in similar cells 

 of different ages ; so that it often happens that only the 

 nucleoli are stained in the younger parts, and only the 

 nuclear framework in the older ones, by the same method. 

 The cause of these differences cannot yet be stated ; but it 

 is not improbable that bodies of various sorts are contained 

 in the so-called nuclear framework. 



336. The most certain distinction between chromatin- 

 globules and nucleoli may be reached by means of the Her- 

 mann-Flemming safranin-gentian-violet methods (cf. 322- 

 324), which give a beautiful red color to the nucleoli and a 

 violet blue to the chromatin-globules, especially with material 

 fixed with chrom-osmic-acetic acid ( 309) or with platinum- 

 chloride-osmic-acetic acid ( 313). Whether these methods 

 give as clear results in all cases must be determined by 

 further studies. 



336a. The general distribution of erythrophilous and cy- 

 anophilous constituents of the nucleus was first recognized 

 by Auerbach in animal cells. These studies have lately 

 been extended to plants by Rosen (I), who recommends the 

 following methods : 



1. Acid Fuchsin-Methylene Blue. The sections are first 

 stained with Altmann's acid fuchsin (cf. 345), then washed 

 successively with picric-acid-alcohol and with water, then 

 stained with methylene blue, soaked in alcohol, and mounted 

 in balsam. 



2. Fuchsin and Methylene Blue, First stain with an aque- 



