Dr. Bolley on the Theory of Dyeing. 489 



are collected. The only portion of Hartig's labours which it is 

 important for us to notice, concerns the explanation of the phse- 

 nomenon of the attraction of colouring matter by the cell-nu- 

 cleus. Maschke expresses Hartig^s views as follows (we also give 

 Maschke's explanation of these observations iu his own words) : — 



''1. Carmine is by no means the only dye taken up by the 

 chlorogen (or chlorophyll) of the cell-nucleus ; the same thing 

 happens with the juice of Phytolacca decandra, litmus, gamboge, 

 sulphate of copper, cinnabar, and ink. 



" 2. The chlorogen is composed of vegetable gelatine and 

 albumen ; and the gluten of wheat consists of the same sub- 

 stances, each of which possesses the property of taking up 

 colouring matter. Animal albumen (white of egg), the fibrous 

 bundles of isinglass before and after solution, the nitrogenous 

 gluten meal of other seeds, and the non-nitrogenous mucilaginous 

 layers of gum tragacanth cells and other mucilaginous cell-walls 

 [Entifickelunrjsgeschichte des P flans enkeims, by Hartig, p. 6), 

 behave similarly with regard to dyes. 



" 3. Chemical action is out of the question, as is also mere 

 adhesion or penetration, since the smallest scarcely perceptible 

 mixture of dyeing matter with the cell-sap colours the chlorogen 

 and that alone, the cell-walls and juices by which it is surrounded 

 remaining colourless. The colouring commences iu a few seconds, 

 and in a few minutes attains its maximum intensity. 



"4. The whole phfenomenon can hardly be explained other- 

 wise than by supposing an extraordinarily rapid passage of the 

 liquid through the chlorogen, which acts as a filter, arresting and 

 accumulating the colouring matter dissolved in the liquid. 



" 5. Among the difi'erent colouring matters that have been 

 emploj'ed, carmine is to be preferred, because bodies coloured 

 therewith remain transparent even when dyed a deep red. 



"If Hartig's observations under head (1) were altogether cor- 

 rect, his views concerning the colouring of the cell-nucleus would 

 contain little to surprise us, especially when considered in con- 

 nexion with the theory which he propounded long since concern- 

 ing the physiological import of this central organ. 



" It is, however, easy to show that the nitrogenous constituents 

 of the cells easily take a colour from pigments applied merely in 

 a state of intimate division, which in the case of carmine, for 

 instance, can alone be the case. 



" When pigments in a state of actual solution are alone cm- 

 ployed to colour microscopic objects, we obviously have the same 

 state of circumstances as in dyeing wool and silk on a large scale, 

 viz. nitrogenous substances and dye-baths. Now it has long 

 been known that dyes possess a chemical affinity for the sub- 

 stance of wool and silk ; it is also known that certain colouring 



