84 



BIOLOGICAL LECTURES. 



magnification. Such an appearance is not to be observed in a 

 stationary somatic cell. 



Thus we see that we can, by the introduction of this property 

 of isolation, trace back highly important and seemingly hetero- 

 geneous phenomena in cell life to a common cause. 



After this digression we may return to the excretophores. 

 The imbedding of foreign particles in the cytoplasm of the 

 excretophores is only the first step in a series of important 

 changes in these cells, which finally terminate in the disintegra- 

 tion of the latter. 



Let us suppose that an excretophore has by mere mechanical 

 action imprisoned in its plasm a number of solid excretory 

 particles. The isolability of the plasma will soon become mani- 

 fest, and these granules will be surrounded by a fluid secretion 

 of the cytoplasm. The waste products, being indigestible and 

 insoluble, the fluid which surrounds them becomes part of a 



definitive structure of the cell. 

 This fluid may be water or may 

 be something else. I cannot a 

 priori decide what the chemical 

 value of the secreted fluid is, 

 because I am not sufficiently 

 familiar with the chemism of 

 bioplasma and know nothing 

 about the chemical constitution 

 of the excretory products. What 

 I have seen is this: In Fig. i I 

 have reproduced a living excre- 

 tophore, which was obtained by 

 teasing out a part of a living 

 animal (Nephelis quadristriata), 

 drawn under a very high magnification (hom. imm. 1.5 mm. 

 comp. oc. 6). In the living cell the cytoplasmic network is 

 not visible, and the nucleus appears only as a light drop sur- 

 rounded by a highly refractive membrane. I have in this figure 

 made a combination, inasmuch as I have added to the drawing 

 of the living cell the nuclear structure {n) and the cytoplasmic 

 threads {cp) as they appear in a good preparation. The upper 



Fig. 



