The Eelations between Marine Animai and Vegetable Life. 403 



One would expect the ammonia present to be slightly diminished 

 by the aeiatioa, and such proved to be the case in two out of the 

 three experiments. In Exp. 122, on the other band, it was distinctly 

 increased. 



Aeration of the water seemed to afifect its bacterial qualities 

 as little as its chemical and physiological, as the following results 

 show. 



Here we see that in one out of the three experiments, the shaken 

 water apparenti}^ contained more bacteria than the unshaken ; in 

 another it contained less, and in the third about the same. After 

 4 days' larvai growth in the shaken water, the number of bacteria 

 was very much larger than with the unshaken water, but after 8 days' 

 growth, the number had become less. These negative bacteriological 

 results as to the effect of shaking the water are in agreement with 

 those of TiEMANN and Gärtner, Leone, Miguel and others^, in 

 which various river and other fresh waters were used. Thus even 

 fourteen days' continuous shaking of the water seemed to bave no 

 appreciable influence. 



The Nitrites present in the Water. 



In the experiments on the purifying effects of bacteria upon 

 sea-water, the disappearance of the ammonia, especially of the free 

 ammonia, was shown to be a Constant attendant on such purification. 

 What are the chemical changes this ammonia undergoes? Is it in 

 turn converted into nitrites and nitrates by the action of nitrifying 



1 Untersuchung des Wassers pag. 536 — 539. 



