HYALINE AND ALVEOLAR PROTOPLASM 263 



The fact is therefore beyond doubt that living protoplasm 

 occasionally exhibits no trace of alveolar structure. 



Among the representatives of the framework theory some 

 have not discussed this difficulty at all, while others have tried 

 to cope with it in various ways. Heitzmann (1883) thinks the 

 apparent homogeneity of such protoplasm can he explained by 

 the fact that the meshes of the framework are so strongly 

 stretched and widened that their nodal points vanish entirely, 

 i.e. pass into filaments of the framework which at the same time 

 become no longer visible on account of their attenuation. This 

 view obtained a certain amount of support from the fact that it 

 is just those pseudopodia which are stretched out, or to a certain 

 extent pressed out over the surface, that often appear homo- 

 geneous ; and it therefore harmonised with Heitzmann's view, to 

 be discussed later, as to the causes of pseudopodial formation. 



Frommann was also quite aware of the existence of homo- 

 geneous protoplasm. Since he cherishes the idea, as has already 

 been described, that the frameworks can be dissolved in the 

 protoplasmic matrix just as easily as they can be formed 

 anew in it, this phenomenon did not in his opinion present any 

 essential difficulty. Flemming (1882), on the other hand, had 

 rather a different conception of the matter. He considers the origin 

 of homogeneous protoplasm possible by the filaments becoming 

 densely crowded together or being temporarily fused. 



Leydig (1883, 1885) was the representative of an essentially 

 different view. As has already been discussed on a former 

 occasion, the homogeneous protoplasm of the pseudopodia of 

 Khizopods was the same in his opinion as the structureless 

 matrix of the protoplasm, his so-called hyaloplasm, which was 

 supposed to have the power of creeping out of the stiff frame- 

 work of the spongioplasm. 



This summary practically exhausts the opinions expressed 

 upon this point, which in any case has a very important 

 bearing upon the protoplasm question. As has been said, the 

 majority of the representatives of the theory of a framework or 

 of fibrillae have not approached the question at all. Kiinstler also 

 has expressed no opinion upon it. In the same way I do not 

 find any discussion of it in Altmann's granular theory, though 

 such a discussion would have great importance, since granules 

 are certainly wanting in homogeneous protoplasm. 



As has frequently been pointed out in the descriptive 

 part of this work, it can be demonstrated with certainty 

 that the apparently homogeneous protoplasm of the pseudo- 



