394 PROF. TH. W. ENGELMANN. 



bined, of which under normal circumstances a certain amount 

 must be taken into each protoplasmic body, is constantly used 

 up during the movements, probably by the giving off of CO2. 



Corti observed the streaming cease in the cells of Char a, 

 when the air was removed by olive oil, as well as after long 

 standing under the best vacuum obtainable under the receiver 

 of an air-pump. Hofmeister^ observed a cessation in Nitella 

 after five minutes in olive oil, and after thirteen minutes in 

 very rarified air. In the first case the movement started again 

 after the restoration of the air in thirty minutes^ and in the 

 second case after twenty-two minutes. 



Kiihne removed the atmospheric air by means of pure 

 hydrogen. After the gas had been passed for more than 

 twenty-four minutes, fresh-water Amoebae fell motionless to the 

 bottom of the drop (they responded in this condition to 

 induction shocks, but a markedly stronger excitation was 

 necessary in this case). Spontaneous movements recommenced 

 seventy- five minutes after the entrance of air. Plasmodia of 

 Myxomycetes and also the protoplasm of Tradescantia hairs 

 showed no further movement, after some hours of contact 

 with hydrogen, and were in active movement again a few 

 minutes after the readmission of air. And even after standing 

 twenty-four hours in hydrogen readmission of air reinduced 

 the movements. I found that contractile cells from the lymph 

 sac of a frog required two hours' transmission of the purest 

 hydrogen through a hermetically sealed moist chamber to stop 

 the movements : most of the cells became spherical. The same 

 happened with fresh-water Amoebse. A drop of hgemoglobia 

 solution after being under similar conditions for ten minutes, 

 no longer showed in a microspectroscope the two absorption 

 bands of oxy-hsemoglobin, which were previously very distinct. 

 Under very long treatment with pure hydrogen protoplasm 

 dies completely, generally first becoming cloudy and forming 

 vacuoles and finally falling to pieces. 



Tarchanofi*,^ following in the steps of Paul Bert's discovery 



* W. Hofmeister, * Die'Lehre von der Pflanzenzelle,' p. 49. 



^ Tarchauoff, 'Arbeiten der St. Petersburger Gesellsch. d. Naturf,,' vii, 



