72 



MANUAL OF HISTOLOGY. 



Fig. 63. Cells with 

 double nuclei, a, 

 from the liver; 6, 

 from the choroidea 

 of the eye ; c, from 

 a ganglion. 



at times attain enormous proportions (fig. 64). Such conditions are in- 

 variably coincident with a process of proliferation in 

 the cell, and will be treated of more minutely when 

 discussing the latter. We must distinguish this truly 

 double or multiple nucleus from another deceptive ap- 

 pearance of two or several more in one animal cell. 

 There are, namely, cellular formations in various fluids 

 of the system, as in the blood (the white or colourless 

 blood-corpuscles) lymph, chyle, mucus, pus, &c. we 

 will call them lymplioid cells which contain originally 

 a simple nucleus ; which when mature may often, under 

 the action of reagents, such as dilute acids, for instance, 

 be made to break up into several pieces, so that the ob- 

 server is deceived into the belief that he has before him 

 cells with several nuclei. 



The question as to whether the body and nucleus of 



the cell possess any further finer texture, cannot at present be answered 



with certainty. 



48. 



Turning now to the chemical constitution of the animal cell, we find 

 ourselves entering upon a field of histochemical inquiry of which little is 

 known : here more than elsewhere does microscopical 

 research in the investigation of the elements of form 

 appear to be far in advance of chemical analysis. 

 In order to follow up this line of inquiry with any 

 hope of success, we should be able to separate the 

 cell from its surroundings, i.e., from elements of 

 tissue; to take it asunder, or resolve it into its 

 various parts, i.e., inucleus, cell-body, membrane, 

 and subject these separately to chemical analysis. 

 Unfortunately this is for the present impossible, 

 and thus the existence of a great gap in our know- 

 ledge is more than sufficiently explained. 



We are in general only able to state so much; 

 that the still very obscure group of protein com- 

 pounds or albuminous principles, with its numerous 

 members and modifications, with certain of the his- 

 togenic descendants of the latter, play the chief 

 part in the constitution of the animal ce41. 



Besides these, as in all other parts of the system, 

 we find as further constituents, water, and moreover 

 usually in considerable amount; also certain mineral 

 matters, and probably also everywhere fats. 



But though, after what has just been remarked, we 

 may look on the protein matters, and their immediate derivatives, as those 

 substances from which the materials for the production of the animal 

 cell are derived, chemical investigation teaches, on the other hand, that the 

 various parts of the latter must be composed of modifications of these, in 

 that nucleus, cell-body, and membrane (when the latter is present) gener- 

 ally display different reactions. Not unfrequently we are obliged to oivn 

 our knowledge of the composition of animal cells as comprehended in 

 these few and general propositions only. In some other cases, however, 



Fig. 64. Multinuclear 

 " giant-cells " from the 

 medulla of the new-born 

 infant 



