Guilliermond - Atkinson — 34 — Cytoplasm 



The ultramicroscopic observations of Fauhe-Fremiet on In- 

 fusoria and sexual cells of the Metazoa, followed by the work of 

 others (Aggazzotti, Marinesco, Mossa, etc.), have confirmed the 

 results of Mayer and Schaeffer on the optically void state of the 

 cytoplasm. Furthermore, observations on living cells of tissue cul- 

 tures by Levi and the micromanipulations of Chambers are equally 

 in accord with these results. It is, however, to be noted that some 

 cytologists, such as Chambers, have designated under the name 

 of hydrosol the state corresponding to the fluid hydrogel of Mayer 

 and Schaeffer. 



The question of the colloidal state of cytoplasm has been much 

 more discussed in connection with plant cells. The first observers, 

 Gaidukov and Russo, using the ultramicroscope, came to the fol- 

 lowing conclusions: The cytoplasm of these cells appears as a 

 heterogeneous structure; its micelles are animated by Brownian 

 movement; the cytoplasm, therefore, offers the characteristics of 

 a hydrosol. This opinion is still held today by Lefeschkin. Price 

 has stated, on the contrary, that the cytoplasm of plant cells most 

 often appears optically empty, i.e., as a hydrogel. However, this 

 author concedes that it may pass from the state of a hydrogel to 

 that of a hydrosol. Pensa has described in plant cells a hetero- 

 geneous structure in a semi-fluid suspension medium, presenting 

 a luminosity always more or less marked. He hesitates to consider 

 it as a hydrogel or a hydrosol. In this substance he believes there 

 is a dispersed and solid phase represented by a few strongly lighted 

 microsomes and a dark liquid phase also containing some micro- 

 somes animated by Brownian movement. 



The work of Lapicque and his students, that of Becquerel, and 

 our work have shown, on the contrary, that the cytoplasm of plant 

 cells takes on the same aspect as that of animal cells. It is always 

 optically empty in living cells and becomes entirely luminous when 

 it is coagulated, appearing like snow. Our research has proved 

 that the diverging results of the men cited above are explained by 

 the fact that these workers neglected to make a comparative exam- 

 ination of the living cells with lateral and direct illumination. That 

 which those writers who recognize a heterogeneous structure of 

 the cytoplasm describe as micelles, corresponds to the microsomes 

 or vacuolar precipitates, which will be discussed later. These are 

 not of micellar rank and are observed quite as well with direct light 

 as with lateral illumination. Furthermore, some authors, like 

 Pensa, seem to have carried out their observations under unfavor- 

 able conditions and to have described cells in which the cytoplasm 

 was already beginning to coagulate. Observations of living mate- 

 rial that we have carried out in the most varied plant cells (epi- 

 dermal cells of Monocotyledons, filaments of Saprolegnia and of 

 other molds, yeasts, etc.), whether with the ultramicroscope or the 

 ordinary microscope, have always shown us the cytoplasm as homo- 

 geneous, optically void, and translucent. 



Today, therefore, it may be recognized as definitively estab- 

 lished that the cytoplasm in plant cells as well as in animal cells 



