PROTOPLASM 5 



motion are not produced directly by the living material itself but by the 

 chemical activities of substances that the protoplasm has formed by its 

 own "vital" activity, in the same way that it produces the ferments, 

 acids, and other substances mentioned above. 



The chief difference seems to be that the latter are discharged from 

 the cell after secretion to be used in other places, while the heat, light, 

 and electricity producing granules are used inside the cell (light granules 

 or photochondria are sometimes used outside). 



By secretion we shall always mean the elaboration of material in the 

 protoplasm by the activity of the latter. The ejectment of this material 

 by the cell or the gland of which it is a part will be termed discharge. 

 Mathews has called the secretory process hyalogenesis, and the particles 

 so formed hyalogens. This is done to avoid using "secretion" in the 

 sense that we use it, as he believes this word to mean what we mean by 

 "discharge." 



The above discussion reduces us to the idea that the cell can produce 

 only a substance or material. The method of producing these substances 

 is practically not known at all, and the directive force that controls the 

 activities of the cell is entirely unknown and a subject for crude specula- 

 tion. 



Technic. The most ordinary methods carried out with the greatest 

 care are the best to use in the study of protoplasm. Flemming's fluid, 

 paraffin sectioning, and iron haematoxylin staining will probably give the 

 truest pictures. Living material, as the bodies of undifferentiated Pro- 

 tozoa, etc., should also be studied under a very moderate pressure. 

 These latter must be examined under an immersion lens with the dia- 

 phragm reduced to get the best optical results. A particularly beautiful 

 picture of protoplasmic structure may be obtained by cutting well-fixed 

 material in celloidin, and either staining in bulk or after sectioning. 

 The lack of shrinkage in such sections, and the fact that one sees a deeper 

 layer than in the very thin paraffin sections, secures a picture that should 

 be studied in connection with the paraffin preparations. One should 

 also examine the tissue alive in salt solution. Pressure is, then, some- 

 times necessary to get a thin enough layer to work with. 



SOME LITERATURE ON PROTOPLASM 



BUTSCHLI, O., 1892. Untersuchungen iiber mikroskopische Schaume und das Proto- 



plasma. Leipzig, Wilhelm Engelmann. 

 WILSON, E. B., 1899. "The Structure of Protoplasm," Journal of Morphology, XV. 



