184 E - A - Schäfer, 



some of the cells, a granular appearance which may be interpreted 

 either as punctated or reticular, according as the attention is directed 

 more to the apparent granules or to the interstices between them. 

 But in the thinned-out pseudopodia nothing of this can be seen. These, 

 and the actively moving margin of the cell from which they spring, 

 look perfectly glassy and homogeneous, and their limits are often 

 difficult to define against the serum by which they are externally 

 bounded. On the other hand, the intra - nuclear network is quite 

 distinct. 



If now the corpuscles be instantaneously killed by the momentary 

 application of a jet of steam to the cover-glass upon which they are 

 flattened out, they are observed to retain absolutely the form and 

 general appearance which they exhibited during life. The intra-nuclear 

 network is distinctly visible, the central protoplasm has the same punct- 

 ated or reticulated appearance, the marginal protoplasm and pseudo- 

 podia remain absolutely clear, and to all appearance structureless 

 (Fig. 4). And it is precisely the same with the subsequent application 

 of fixing reagents and the staining of the cells by haematoxylin and 

 other dyes. The reticular structure of the nucleus is beautifully shown, 

 the granules of the central protoplasm are more or less stained, the 

 staining of the marginal protoplasm and of the pseudopodia, although 

 faint, is uniform ; it reveals no trace of a reticulum and enchylema l ). 



*) Stricker, (Arbeiten a. d. Institute f. allg. u. exper. Pathologie, 1890) has 

 recently published a photograph of a white corpuscle of Proteus anguineus taken 

 instantaneously by the electric microscope. The corpuscle is nearly spherical but 

 has one small rounded pseudopodium projecting beyond the body of the cell, The 

 main cell-substance exhibits a beautifully reticular appearance but the pseudopodium 

 appears entirely devoid of structure. 



Bütschli (Heidelberg Verhandl., 1889 und 1890) who looks upon the reticular 

 appearance of protoplasm as due to the fact of its being actually formed of a sort 

 of froth (? emulsion) produced by the intimate commingling of two dissimilar fluids, and 

 who adduces a large number of observations in support of this view, nevertheless 

 admits that it is impossible to observe this structure in the ectoplasm and especially 

 in the pseudopodia of many protoplasmic organisms. He nevertheless is of opinion 

 that it may be present here also but that the spreading out of the protoplasm into 

 the pseudopodium has reduced the protoplasm to such a degree of tenuity that its 

 structure has become invisible. This explanation cannot however be accepted; because 

 there is a sharp line of demarcation between the reticulated or punctated cell- 

 substance and the pseudopodial protoplasm, and not the gradual shading off of the 



