PROTOPLASMIC STRUCTURE 23 



the nuclear membrane with the fibers in the cytoplasm, while Stras- 

 burger believes in its structural independence of the cytoplasm. The 

 masses of chromatin, so conspicuous in many stained nuclei, are much 

 more substantial than the linin network on which they are distributed. 

 The exact relations of these two nuclear elements, the linin network and 

 the chromatic masses, are still in doubt, but in one way or another they 

 are surely structurally connected. By some competent observers, espe- 

 cially by certain neurologists, the chromatin bodies are considered to be 

 chemically the most essential part of the nucleus. The nudeolus may be 

 only one, or there may be many, sometimes bunched together into what 

 seems a solid mass. These are situated in the nuclear sap, and are uncon- 

 nected and unattached to either the linin network or to the chromatic 

 granules. The nuclear membrane, dividing the nucleoplasm from the 

 cytoplasm, is very delicate and perfectly transparent. Through it the 

 important interchanges of the nucleus 'and the cytoplasm continually 

 take place. 



The cytoplasm constitutes much the larger mass of the majority of 

 cells. In structure it appears to be much simpler than the nucleoplasm, 

 having only two elements, a reticulum (or something similar in appear- 

 ance) and a homogeneous transparent fluid pervading and surrounding 

 it. Leydig and Schafer suppose the more liquid portion to be the essen- 

 tial part, but many authorities so consider the network or reticulum. 

 Some, of late, have maintained that the " reticulum" is artificial. A 

 more reasonable supposition, however, is to recognize in both indispen- 

 sable ingredients of the vital substance. 



The Structure of Protoplasm. This has been discussed by many 

 biologists, but the results of their work are so various that their theories 

 are of slight importance. The differences in what observers describe as 

 seen under the high powers of the microscope depend more on mental 

 differences than on anything else. This is a good illustration, as modern 

 psychology has pointed out, that what one sees, or thinks he sees, depends 

 to a considerable extent on the contents of his mind. The most likely 

 supposition is that identified with the names of Kolliker, Kiinstler, and 

 especially of Biitschli. The researches of Biitschli are classical, par- 

 ticularly those in which he has imitated with emulsions the movements 

 of some varieties of protoplasm. On this supposition protoplasm, or 

 at least cytoplasm, consists of a mass of minute spheres filled with trans- 

 parent liquid, these being crowded together so closely that their liquid 

 walls coalesce and form lines more or less straight and angular. It is 

 only because of the optical conditions that the largest of these inter- 

 secting spherules appear to constitute a network. The spherules are 

 freely movable and roll upon each other without breaking the continuity 

 of the protoplasmic element which forms their wallsv These exceedingly 

 minute droplets of liquid (called chylema by Biitschli) are, according to 

 this theory, the essential elements of protoplasm. Whether the fine 

 fibrils and the minute granules which sometimes are to be found in the 

 liquid between the droplets are incidental, or have some secondary func- 



