6 VICTOR E. SHELFORD. 



With reference to fish breeding plau->, the gas content of the 

 water was determined on tour occasions. To make collect ion^ in 

 ponds 5r over a sandy bottom required taking advantage of the 

 sand areas made by artificial filling. Since there is little ban- 

 sand in ponds ~ja and I4/; the collections were made over the 

 vegetation. 



TABLK V. 



Oxygen content in cubic centimeters per liter. Depth 35-40 centimeters. 

 Sample collected at the bottom or among the upper two inches of branches of 

 aquatic plants as indicated. 



The table shows high oxygen content over sandy bottom, 

 oxygen probably sufficient for most fish over vegetation, and no 

 oxygen on the bottom where vegetation was removed in July and 

 August. 



TABLE VI. 



SHOWING CO; CONTENT OF WATER. 



Depth 35-40 cm. (i) Over sandy bottom. (2) Over vegetation. (3) Over 

 bottom with vegetation removed. 





>i 



The water was alkaline at points showing no ("()._.. The tables 

 do not show the uniformity that might be expected. This ma\ 

 be explainable on the basis of the place of collection. (.'/Kirn, 

 for example, which was the plant removed from the bottom ol 

 ponds i. and $c, grows on bottoms of mixed sand and humus or on 

 a bottom covered \\iili humus, and sufficient care \\a- not taken 

 in selecting places of collection, to make the dillcicncc^ heir ol 

 importance. 



