116 GENERAL PHYSIOLOGY 



constituents of the two essential cell-elements, the protoplasm and 

 the nucleus. 



The proteids, which are the sole general chemical constituents 

 of the cell, occur in both the protoplasm and the nucleus, but a 

 very remarkable difference between them has been discovered. 

 It has been found that the compounds of proteids, containing 

 phosphoric acid, the so-called nucleins, preponderate greatly in 

 the nucleus, 1 while in the protoplasm they seem to be wanting 

 entirely, or at least to appear only in combination with other pro- 

 teids as nucleo-albumins ; the protoplasm, on the other hand, is 

 constructed chiefly of simple proteids and proteid compounds that 

 lack phosphorus. The employment of a simple chemical method 

 confirms this fact. As Miescher ('74) has shown, the nucleins, in 

 contrast to all other proteids, resist the digestive action of the 

 gastric juice. If, therefore, cells of very different kinds be brought 

 under the influence of artificial gastric juice, all other proteids are 

 digested, while the nucleins remain. It is then found that the 

 whole protoplasmic body is digested, while the nuclei are left with 

 an inconsiderable decrease in volume and a somewhat ragged 

 contour. If, now, the remaining substance of the nuclei be tested 

 with the known nuclear stains, it is shown that what is wanting 

 is the nuclear sap, 2 and perhaps the achromatic substance also, 

 for the whole remaining mass takes up the nuclear stain more 

 or less strongly. It follows, therefore, that the chromatic 

 substance and the nucleoli consist of nucleins, while the pro- 

 toplasm of the cell is composed of other proteids. Lilienfeld 

 and Monti ('93), in Kossel's laboratory, have endeavoured to 

 prove by means of a micro-chemical reaction that phosphorus is 

 localised especially in the nucleus. If ammonium molybdate be 

 added to a substance containing phosphoric acid, a compound is 

 formed, phospho-molybdic acid, which with pyrogallol takes on a 

 dark brownish-black colour. Lilienfeld and Monti were able to 

 show that in a great variety of cells the nuclei stain black because of 

 this reaction, while the protoplasm is left unstained ; but it should 

 be mentioned that soon after the publication of their results 

 Raciborski, Gilson and Heine raised the objection against the re- 

 action that there was simply an accumulation of ammonium 

 molybdate in the nucleus, which is analogous to the accumulation 

 there of nuclear stains. Hence caution is still necessary in drawing 

 conclusions from this reaction. 



The carbohydrates appear to be limited to the protoplasm ; at 

 least, thus far no carbohydrates have been found in the nucleus. 

 In the protoplasm they appear not rarely as solid constituents, e.g., 

 glycogen in the form of scales and irregular particles in the proto- 

 plasm of liver-cells, starch-grains in general in the protoplasm of 



1 Gf. Kossel ('91). 



a Cf. Haifa tti ('91, '92). 



