FIG. 5. Diagram of a cell, 

 highly magnified. (SCHAFER.) 

 p, protoplasm, consisting of 

 hyaloplasm and a network of 

 spongioplasm ; ex, exoplasm ; 

 end, endoplasm, with distinct 

 granules and vacuoles; 

 c, double centrosome ; n, nu- 

 cleus ; n', nucleolus. 



THE STRUCTURAL BASIS OF THE BODY ,., 



plasm between them will be converted into alveolar partitions between the 

 droplets. In many an egg cell, where there is a growth of protopla*, 

 this building up of food into reserve materials, the development of such 



an alveolar structure can be followed in the 

 living protoplasm, and such cells when n, 

 show a marked alveolar structure whether ex- 

 amined fresh or in the hardened and stained 

 condition. Such a protoplasm would be prac- 

 tically an emulsion of one fluid in another and 

 according to Biitschli artificial emulsions, made 

 by mixing rancid oil with sodium carbonate 

 solutions, may show under the microscope a 

 very close resemblance to cell protoplasm 

 (Fig. 6), and may even exhibit amoeboid 

 changes of form in consequence of the diffusion 

 currents set up at the surface of the drop 

 between its contents and the surrounding 

 water. Most histologists are in accord that 



none of the above theories can be regarded as applicable to all forms of 



protoplasm, but that during the life of a cell its protoplasm, as observed under 



the microscope, may be either 



hyaline and structureless or may 



present any of the structural modi- 

 fications described above, according 



to its state of nutrition and the form 



in which its metabolic products are 



laid down in the cell. Of course 



it is possible that, even in the 



apparently hyaline protoplasm, a 



structural differentiation is still pre- 

 sent, but is invisible owing to the 



minute size of its constituent parts 



or an identity of refractive index 



between the alveolar walls and their 



contents. The fact that every 



chemical differentiation occurring 



within the colloidal mass will tend 



to cause differences of surface ten- 

 sion, and therefore formation of 



droplets, -shows that an alveolar 



structure, i.e. one in which there is 



a large number of surfaces separat- p 1G . e. A, protoplasm of ^an ep 



ing heterogeneous mixtures inside ^^^nisionof oUveoil. 





the cells, must be of very common 



i ***** where it is not detectable under the i m V* 



occurrence, even in cases where 



Such a structure must be present, at any rate, in 



those cases where, apart 



