244 ^OME ASPECTS OF CELL-CHEMISTRY AND CELL-PHYSIOLOGY 



nature. Such terms as " erythrophilous," " cyanophilous," and the 

 like have therefore no meaning apart from the chemical compo- 

 sition both of the dye and of the substance stained. ^ 



The constancy and accuracy of these reactions await further test, 

 and until this has been carried out we should be careful not to place 

 too implicit a trust in the staining-reactions as an indication of chemi- 

 cal nature, especially as they are known to be affected by the pre- 

 ceding mode of fixation. They afford, nevertheless, a rough method 

 for the micro-chemical test of the proportion of nucleic acid present 

 in the nuclear structures, and this in the hands of Heidenhain has 

 led to some suggestive results. Leucocytes stained with the Biondi- 

 Ehrlich mixture of acid fuchsin and methyl-green show the following 

 reactions. Cytoplasm, centrosome, attraction-sphere, astral rays, and 

 spindle-fibres are stained pure red. The nuclear substance shows a 

 verv sharp differentiation. The chromatic network and the chromo- 

 somes of the mitotic figure are green. The linin-substance and the 

 true nucleoli or plasmosomes appear red, like the cytoplasm. 

 The linin-network of leucocytes is stated by Heidenhain to consist 

 of two elements, namely, of red granules or microsomes sus- 

 pended in a colourless network. The latter alone is called " linin " 

 by Heidenhain. To the red granules is applied the term "oxychro- 

 matin," while the green substance of the ordinary chromatic network, 

 forming the " chromatin " of Flemming, is called " basichromatin." ^ 

 Morphologically, the granules of both kinds are exactly alike,'^ and 

 in many cases the oxychromatin-granules are found not only in 

 the "achromatic" nuclear network, but also intermingled with the 

 basichromatin-granules of the chromatic network. Collating these 

 results with those of the physiological chemists, Heidenhain concludes 

 that basichromatin is a substance rich in phosphorus {i.e. nucleic 

 acid), oxychromatin a substance poor in phosphorus, and that, 

 further, " basichromatin and oxychromatin are by no means to be 

 regarded as permanent unchangeable bodies, but may change their 

 colour-reactions by combining with or giving off phosphorus." In 

 other words, " the affinity of the chromatophilous microsomes of the 

 nuclear network for basic and acid aniline dyes are regulated by cer- 

 tain physiological conditions of the nucleus or of the cell."^ 



This conclusion, which is entirely in harmony with the statements 

 of Kossel and Halliburton quoted above, opens up the most interest- 

 ing questions regarding the periodic changes in the nucleus. The 

 staining-power of chromatin is at a maximum when in the preparatory 

 stages of mitosis (spireme-thread, chromosomes). During the ensuing 

 growth of the nucleus it always diminishes, suggesting that a com- 



iCf. p. 127. 2 '94, p. 543. 3/.^., p. 547. </.f.,p. 54^- 



