THE EFFECTS OF CARBON DIOXIDE ON THE CON- 

 SISTENCY OF PROTOPLASM. 



M. H. JACOBS, 



I MVERSJTY OF PENNSYLVANIA. 



INTRODUCTION. 



It has been shown by a number of recent investigators, using the 

 microdissection and other methods, that the consistency of the 

 protoplasm of different cells may vary from that of a liquid almost 

 as mobile as water to that of a solid gel. It has also been shown 

 that within the same cell at different times there may be almost 

 equally striking differences. For example, Bayliss ('20) has re- 

 ported that when the ectoplasm of an Amoeba is observed with the 

 ultramicroscope it appears to be filled with fine brilliant particles 

 in rapid Brownian movement an indication of the liquid state. 

 On electrical stimulation the movement suddenly ceases, to be re- 

 sumed when the stimulation is discontinued. Evidently in this 

 case stimulation is attended by a solidification, or at least by a very 

 considerable increase in the viscosity of the protoplasm. Another 

 important example is furnished by cells in the act of division. 

 Heilbrunn ('15) and Chambers ('17), using entirely different 

 methods, have both shown that during the cleavage of marine ova 

 there is with each cell-division a regular cycle of changes leading 

 from a more liquid to a more solid condition and back again. It 

 seems very likely that these changes play an important part in the 

 actual mechanics of the division process. A third example is fur- 

 nished by various cases of amoeboid movement, where changes in 

 protoplasmic consistency are thought by some of the most recent 

 workers on the subject (especially L. Loeb, '02, '20, '21, etc.) to 

 be concerned in actually producing the movement. A consider- 

 able number of other cases, some definitely established, others 

 merely probable, could be mentioned. It seems certain that 

 changes in protoplasmic consistency are not only of widespread 

 occurrence, but are also of great physiological importance. 



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