of Phosphorus in Animal and Vegetable Tissues. 475 



Results of the Method. 



I. General. The chromatin of all nuclei gives, after eighteen 

 hours' treatment with the nitric-molybdate reagent a strong 

 phospho-molybdate reaction. This is so marked that the nuclei 

 appear under ordinary microscopic magnification as if they were 

 stained with a dark-green dye for the express purpose of showing 

 the chromatin structures. Even the finer fibrils constituting the 

 so-called reticulum are prominently brought out. This is well 

 illustrated in the nuclei of the epithelial cells of the skin, alimentary 

 tract, renal tubules, and olfactory region, and of the muscle fibres, 

 liver cells, testicular and ovarian cells, nerve cells (spinal cord), 

 pancreatic cells, connective tissue cells, and leucocytes of Meno- 

 branchus (Necturus) later alis and Amblystoma punctatum. In veget- 

 able cells, as shown in Erythronium americanum, the same result 

 was found. In brief, wherever true chromatin was found, there the 

 reaction for phosphorus was obtained. In the chromatin of the 

 mitotic loops in dividing animal and vegetable cells, no reaction 

 more marked than in the chromatin of the resting nuclei was in any 

 case obtained. This fact definitely contradicts the 'view of Lilien- 

 feld* that the chromosomes in mitosis are composed of nucleic acid 

 only, a view which Heine,t as a result of experiments in staining 

 with mixtures of dyes, also rejected. The phosphorus in nucleic 

 acid amounts to 9 10 per cent., but in nuclein it is 3 4 per cent. 

 If Lilienfeld's view is correct, then the reaction for phosphorus 

 in the chromosomes should be at least twice as marked as in resting 

 chromatin elements, taking volume for volume. The results 

 obtained by Lilienfeld in his staining experiments must be explained 

 on some other hypothesis than that which he adopted. 



The eosinophilous nucleoli in animal and vegetable nuclei give a 

 strong reaction for phosphorus, but less marked than in the case of 

 the chromatin. On the other hand, the nucleolar elements in the 

 nucleus of the ovary of Erythronium which, as I have pointed out,J 

 are rich in " masked " iron, give a deep reaction for phosphorus. 

 A similar result was obtained in the nucleoli of the nuclei of the 

 embryo-sac of the same form, in the peripheral nucleoli of the 

 maturing ovarian ova of Menobranchus, in the nucleoli of Corallorhzza 

 multiftora and of tipirogyra, all rich also in " masked " iron. The 



* " Ueber die Wahlverwandtschaft der Zellelmente zu gewissen Farbstoffen," 

 'Verb. Berl. Physiol. Gesell.,' ' Arcb. fur Anat. und Phys.,' Phys. Abth. 1893, 

 p. 391. 



f "Die Mikrocbemie der Mitose, zugleich eine Kritik mikrocbemischer Me- 

 thoden," ' Zeit. fur Physiol. Chemie,' vol. 21, p. 494, 1895-96. 



J " On the Distribution of Assimilated Compounds of Iron, other than Haemo- 

 globin and Hsernatins, in Animal and Vegetable Cells," ' Quart. Journ. Micr. Sci.,' 

 vol. 38, p. 175, 1895. 



VOL. LX1II. 2 N 



