172 PROTOPLASM 



and fixed protoplasm. The so-called protoplasmic granules 

 were in great part merely the nodal points of the frame- 

 work, but there were frequently also numerous granules of 

 various kinds present, which lay originally, at least, in the 

 substance of the framework. The fact that the striated, 

 radiating, and confused fibrous structures, which were 

 frequently observed in the protoplasm of certain cells, were 

 only modifications of the spongy framework was quite 

 certain in his opinion, and was clearly proved by their 

 frequent transitions into ordinary protoplasm. In conse- 

 quence of this view, which was only occasionally slightly 

 shaken by his referring to vacuolar protoplasm (1885, 

 footnote on p. 2), he arrived, like Frommann, at the opinion 

 that the surface of the protoplasm must be porous, and 

 interrupted by finer or coarser gaps, which were subject to 

 great change in shape and size. He therefore conceives of 

 the surface of the cell as porous, somewhat in the same way 

 as that of a bath sponge. With this is connected the 

 fact that the intervening substance or contents of the frame- 

 work his " hyaloplasm " must be " soft, clear, and semi- 

 fluid," and in any case not capable of being mixed directly 

 with the surrounding water, since he ascribes to it certain 

 curious peculiarities, as a further consequence of the concep- 

 tion just discussed. Thus the hyaloplasm is supposed to 

 " creep out, as it were," from the framework, and form the 

 pseudopodia of Protozoa or other cells ; it would further 

 form in a similar manner (1) the sensory bristles, knobs or 

 hooks, the auditory setae, the visual rods, and the real nervous 

 substance in general ; (2) the contractile material of cilia and 

 muscles; (3) the homogeneous substance of the cuticular 

 layers ; and (4) certain secretory masses. 



From this conception it follows at once that Leydig 

 sees in the hyaloplasma the real living, contractile, and 

 nervous substance, while the framework his spongioplasma 

 must only perform the function of support. But he 

 did not remain perfectly consistent with himself, since in 

 1885, p. 105, he believes he has seen the cilia on the 

 epithelial cells of the olfactory mucous membrane of the cat, 

 arising as processes of the spongioplasma, and on p. 161 



