Study of Spirogyra nitida. 217 



sulphuric acid, but that a deposition of starch did not occur 

 until the eighth day. It is not, then, injurious when in 

 small quantity. 



Since the amine is readily absorbed by mineral acids, 

 yielding with them stable salts, we have a ready means by 

 which to detect and estimate it, and to answer some of 

 these questions for Spirogyra. 



Newly formed threads of Spirogyra were placed in a 

 flask of distilled water which had been rendered ammonia- 

 free. A culture mixture, containing the nitrogen as nitrate, 

 provided the necessary inorganic food. As the plant grew 

 the gases were pulled out of the flask by means of an air 

 current and caught in sulphuric acid, from which the 

 trimetln lamine was isolated. The apparatus in which this 

 work was carried out was arranged in the following 

 manner : 



Air was admitted to the flask by means of a tube extend- 

 ing almost to the bottom of the liquid, and having a short 

 arm attached to a U tube containing sulphuric acid. This 

 served to free the entering air from ammonia and organic par- 

 ticles. Another tube, having a short limb, carried off the 

 air which by this contrivance was compelled to travel 

 through the entire depth of liquid. This tube was attached 

 to a Liebig potash bulb containing sulphuric acid, which 

 effectually prevented any amine from passing through and 

 so occasioning loss. Between the absorption bulb and the 

 drop-aspirator, by which a steady air-current was main- 

 tained, was fixed another U tube holding sulphuric acid, 

 to prevent any gases from decomposing organic matter 

 (which the river water might contain) pushing back into 

 the bulbs. The air current was regulated by means of 

 ground-glass stop-cocks. 



As soon as the threads showed any tendency to collect 

 and sink together in the bottom of the flask, the long 

 masses which waved above were carefully lifted out and 

 transferred to a new culture -solution, so that all decompos- 

 ing cells should be eliminated. 



