GuilHermond - Atkinson — 10 — Cytoplasm 



then, under its immobile surface, flows with extreme rapidity. In 

 addition, the different veins and the flowing, continuous layers com- 

 prising the Plasmodium, show very curious, rhythmic but not syn- 

 chronous, pulsations. These are rendered quite visible by motion- 

 picture photography. Each vein shows an alternation of systole 

 and diastole ; each outer layer flows by jerks over the substratum, 

 becoming alternately thicker and thinner (CoMANDON and PiNOY, 

 Seifriz). 



Under sufficiently high magnification the Plasmodium seems to 

 be formed of an homogeneous substance, holding in suspension in- 

 numerable granules, in particular, lipide droplets and ingested 

 debris, whose incessant displacement in different directions reveals 

 with great clearness the existence of cytoplasmic currents. 



These currents are very irregular. They may be rapid or may 

 even rush along in a vein and, at a given instant, 

 V\ /# they will immediately slow up, then change direc- 



^ " tion, accelerate, retard again, return to the orig- 



inal direction and so on. In each vein the same 

 irregularities are observed but without any syn- 

 chronism whatever. Thus, the movement of the 

 entire mass of the Plasmodium in one direction 

 expresses the sum of all these movements in dif- 

 ferent directions and indicates that in this appar- 

 ent disorder, the protoplasm flows more in one 

 direction than in the other ; namely, in the direc- 

 tion of the advance of the organism. 



Now these characteristics of protoplasm have 

 nothing unusual about them. Microscopical ex- 

 of the diff^enrdire™ aminatious of the contents of the most varied cells 

 tions taken by proto- reveal that there, too, protoplasm behaves as a 



plasmic currents in a ^ . , , , mi it i • i -x i i i 



portion of the vein- fluid substance. The bodies which it holds sus- 

 piTsmodium.'"" °^ ^ pended in it are in most cases more or less rapidly 



carried along in its multiple currents. Here, as in 

 the extended body of the Plasmodium, these currents run side by 

 side, separated by calm borders. They ramify, anastomose and 

 change constantly. These are the phenomena of cyclosis for which 

 the cells of Elodea canadensis and the staminate hairs of Tradescan- 

 tia or of Celandine are classic subjects for observation. These 

 phenomena are found again in Spirogyra in which they appear 

 with great distinctness and of which more will be said later on. 



All these facts indicate, therefore, that cytoplasm flows. This 

 presupposes a mobility of molecules found only in a liquid state, 

 which, in a word, is the essential property of a liquid state. 

 These movements are, however, much less accentuated in some 

 cases. They seem to be nearly absent in certain plant cells, among 

 others in yeasts and various fungi, in which the cytoplasm appears 

 to be much less fluid and shows no displacement of granules. This 

 seems also to be the case in most animal cells. 



Other arguments resting especially on observations of plant 

 cells have been brought forward in favor of the fluid state of cyto- 



