THE CHEMISTRY AND PHYSICS OF THE CELL 55 



Loeb says, " By cellular structure we understand the fact that 

 there must be a definite maximal distance between the elements 

 of the protoplasm and the nearest nucleus." 



It should be mentioned that certain cells, such as bacteria 

 and algae, seem to have no true nuclei, but Macallum l found 

 that the forms he examined gave reactions for phosphorus and 

 iron in a similar way to the nucleoproteids of a nucleus, suggest- 

 ing that in such cells the nuclear elements are diffused through 

 the cell rather than differentiated. To quote Wilson : " The 

 terms f nucleus ' and ( cell body ' should probably be regarded 

 as only topographical expressions, denoting two differentiated 

 areas in a common structural basis." 



Because of the relative acidity of the nuclei they are electric- 

 ally negative to the cytoplasm, particularly when in karyokine- 

 sis. Sperm-heads in isotonic cane-sugar solution move rapidly 

 2000 microns a minute toward the anode, when a current 

 is passed through the solution ; and leucocytes also go toward the 

 anode under the same conditions, the rate depending upon the 

 proportion of nucleoplasm and cytoplasm, large leucocytes some- 

 times even going slowly toward the cathode. The Sertoli cells 

 of the testicle, which have a round mass of cytoplasm with a 

 number of miniature spermatozoa heads at one side, orient 

 themselves in the current so that the side or end containing the 

 spermatozoa drags the mass of cytoplasm toward the positive 

 pole. 



THE CYTOPLASM 



The cytoplasm, as before mentioned, contains all of the 

 primary cellular constituents, and also such secondary constit- 

 uents as the particular cell possesses. Nucleoproteids are un- 

 doubtedly present in unknown proportions, but with the 

 nucleic acid well saturated by proteids, and perhaps also to 

 a large extent combined with carbohydrates to form the 

 glyconucleoproteids. Sometimes the nucleoproteids of the 

 cytoplasm may be partly of the unsaturated class, and show 

 an affinity for basic stains, as in the case of the Nissl bodies 

 of the nerve-cells, and perhaps also the cytoplasm of plasma 

 cells. The great question concerning the cytoplasm is its struc- 

 ture whether homogeneous, alveolar, areolar, fibrillar, foam- 

 like, or granular. On a previous page have been mentioned the 

 experiments of Hardy, which show that homogeneous solutions 

 of proteid, when fixed by the same reagents as are used in the 

 customary fixation of histological materials, may show quite the 

 1W Studies from the University of Toronto, " 1900. 



