42 



INFLUENCE OF CHEMICALS 



Perform the experiment, using carbon dioxide from a suitable 

 generator, and compare data with above. The exclusion of the 

 oxygen may also be accomplished by mounting the objects in 

 olive oil. Removal from the oil and washing in fresh water will 

 be necessary to secure a resumption of the movement. It is to 

 be kept in mind that rough handling will stop the movement in 



Fig. 22. Kipp's apparatus for production of hydrogen. The middle globe is 

 partly filled with strips of zinc and a weak solution of hydrochloric or sulphuric acid 

 is poured into the bent thistle tube until it rises into the chamber containing the zinc. 

 The gas escapes through the outlet at the side and passes through a solution of potas- 

 sium permanganate in the wash bottles. Closure of the stopcock in the outlet tube 

 drives the acid back into the upper chamber and stops the evolution of gas. 



consequence of the shock given. The organism is not subject 

 to the influence of hydrogen under ordinary conditions, and as 

 this element has a low chemical intensity and narrow range of 

 special affinities it does not set up any disturbance in living matter 

 Its action in the above experiment is therefore due to the exclu- 

 sion of the atmospheric oxygen from the cell. The air in the 



