CHEMISTRY OF THE PROTOPLAST 



67 



visible alterations. The study of the changes which occur when the protoplasm 

 dies is obviously of the highest importance. 



The physical characters of the dead protoplast, and especially its power of 

 absorbing colour-stains in varying degree, give us a valuable suggestion and indi- 

 cation of what may be the probable nature and structure it possessed during life. 

 The absorption of stains can be used, however, only with the utmost caution as 

 a test of the chemical nature of any given part, for absorption is dependent upon 

 physical rather than chemical properties l . Thus carbon in the form of a diamond 

 is non-absorbent, but in the form of charcoal has marked absorptive powers, and 

 hence can decolorize coloured fluids. Substances are known, both in technical 

 industry and in science, which may be rendered capable of absorbing pigments by 

 a special mode of preparation, although they retain the same chemical constitution 2 . 

 It is only in the light of these facts that any conclusions can be drawn from the 

 cyanophil or erythrophil character of the nucleus, or from the basophilous or 

 eosinophilous behaviour of the plasma 3 . 



Percentage Composition, In any analysis of the entire protoplast, various sub- 

 stances not actually forming part of the living substance are necessarily included, and 

 these are also present in the plasmodium of a Myxomycete. Hence the percentage 

 composition of the latter is as incapable of giving an empirical or percentage 

 formula for the plasma, as is the analysis of a highly protoplasmic tissue from which 

 the cell-walls have been removed. Reinke 4 found that the plasmodium of 

 Aethaliuni septiatm contains, when fresh, as much water as is found in moderately 

 turgid tissues (Sect. 33). 



The plasmodium contains 71-6 per cent, of water, of which 66-7 per cent. 

 may be removed by strong pressure. In 100 parts of the air-dry materials were 

 found : 



Pepsin and Myrosin . . ". 4-8 per cent. 



Vitellin 5-0 ,, 



Plastin ..... 27-4 ,, 



Asparngin and other amides . i-o ,, 



Peptone and Peptonoid substances 4-0 ,, 



Lecithin 0-2 per cent. 



Glycogen . . 4.7 



Sugars . -3-o 



Cholesterin . . . . 1-4 ,, 



Fatty acids, soluble in ether . 4-0 



In the remaining 44-5 per cent, a number of organic substances are included, 

 as well as the ash constituents, of which calcium carbonate forms 27-7 per cent. 

 The nucleins, which are not specially mentioned here, comprise in leucocytes, 

 according to KosseP, 34-26 per cent, of the entire weight. 



The so-called active albumin. It is impossible at present to say exactly what 

 changes the proteids of the protoplast undergo on death. Loew and Bokorny have 

 constructed a formula for living proteid, and suppose that vital activity is centered in 



1 Ostvvald, Lehrbuch der allgern. Chemie, 1891, 2. Aufl., Bd. I, p. 1093. 



2 See Pfeffer, I.e.; A. Fischer, Unters. uber Cyanophyceae u. Bacterien, 1897, pp. 5, 118. 



3 Rosen, Cohn's Beitrage, 1895, Bd. vn, pp. 225, 304, and the literature there cited. See also 

 Lilienfeld, Centralbl. f. Physiol., 1893, Bd. vu, p. 621 ; A. Fischer, I.e., Heine, Zeitschr. f. physiol. 

 Chemie, 1896, Bd. XXI, p. 494. On the alkaline and acid reactions of protoplasm see Sect. 86. 



4 Reinke, Unters. a. d. Bot. Lab. in Gottingen, 1881, Heft 2, p. 54. See also Hofmeister, 

 Pflanzenzelle, 1867, p. 2. 



5 See O. Heitwig. Die Zelle u. d. Gewebe, 1893, p. 17. 



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