504 



KNOWLEDGE & SCIENTIFIC NEWS. 



[August, 1906. 



one. This in turn altered its shape, and under the 

 influence of the attraction of tlic six small drops as- 

 sumed the form of a hexagon, the least pronounced 

 angle being situated in front of the farthest distant 

 drop. 



Now tlie I'Dregoing effeiis of cohesion, \\ hit h had so 

 far been unknown, seem to play a pre-eminent part in 

 connection with certain physiolog'ical phenomena. The 

 segmentation of the vitellus (yoll< of eggs) during in- 

 cul);ition, had, e.g., so far been one of the most enig- 

 matical phenomena of animal life, there being no known 

 phy.sical force under the influence of which a similar 

 effect might have been produced. Now the conditions 

 of incubation are quite similar to tho.se obtained in the 

 pre.sent experiment,' the high temperature resulting at 

 the surface of the egg in a vaporisation, which, in the 

 surface portion of the yolk, produces a concentration. 





Fig. S- 



Thus currents of liquid (due to diffusion) arise, v\hich in 

 turn, as in the above experiment, must result in a sub- 

 division or segmentation of the mass. The artificial 

 segmentation obtained by Leduc (Fig. 6) will be found 

 to be strikingly similar in appearance to the natural 

 segmentation of the y'olk. 



Now all lamellar ;md \acuolary structures in living 



> ^ ^ ^^'^ ;>i ^- vv.l',^'^? 

 /}^ :^\^ yr ^^ •>, V- -^ y^ 



Fig. 6. 



organisms are made up of may be obtained in a similar 

 way. Protoplasm in turn consists of the same struc- 

 tures, while those artificially obtained by Leduc show- 

 phenomena quite analogous to the lamellar, cellular, 

 and vacuolary structures of living protoplasms. These 

 are retractile, their cohesion increasing in retraction in 

 quite the same way as that of coagulating colloids. !n 

 fact, real colloids seem, in the experiments at issue, to 

 be obtainable from solutions of crystallinic substances. 



This would constitute another transition stage between 

 categories hitherto distinct, while explaining and 

 artificially reproducing the physical mechanism of 

 coagulation. Cells and lamellar structures obtained in 



Fig. 7- 



virtue of diffusion and cohesion, by the aid of such solu- 

 tions and in microscopical powder therein suspended, 

 are represented in Figs. 7 and 8. 



The same phenomenon would, moreover, afford a 



physical explanation of the much-discussed pheiiomo 

 non of flocculation in turbid liquids. 



/\s, finally, the conditions of Leduc's experiments are 

 realised also in natural water, and especially in sea 

 water, in which foreign particles are always in sus- 

 pension, producing currents of diffusion due to their 

 dissolution, the external agreement in the shape and 

 f>ehaviour of natural organisms and protoplasms on 

 one hand and the artificial structures obtained by 

 Leduc on the other would be fully accounted for. 



