PROGRESS IN BIOLOGICAL INQUIRIES, 1937 59 



of the chemical composition of trout of different ages. This work 

 lias been severely hampered by lack of both equipment and skilled 

 assistants but progress is being made. As this phase of the work 

 progresses it is hoped to include even the egg in its early develop- 

 ment because here must lie some of the secrets of producing sound 

 trout. Special attention is now being devoted to the exchange of 

 nutrients between the sac and the fry in the period just after the 

 eggs are hatched. 



In the interest of improving the practical diets now used in the 

 hatcheries special studies have been completed during the past year 

 of such products as linseed meal, meats preserved in acid, various 

 fish meals and seal meal. Linseed meal has been freed from 

 its poison by steaming and pressure cooking. These processes pro- 

 vide a nontoxic meal that still retains the important property of 

 binding water and liquids such as meat juices. 



In the study of preserved meats it has been found that acids such 

 as hydrochloric, phosphoric, and acetic, are satisfactory especially 

 when their action is supplemented by that of molasses. After long 

 storage of ground meats and molasses the meat tends to liquefy and 

 to lose some of its value probably due to the loss of factor H. No 

 evidence of toxicity has been discovered and the hydrolysis is only 

 partial because there is little increase in amino nitrogen. A satis- 

 factory method of keeping meats for long periods without spoilage, 

 without deterioration in nutritive value and without loss of physical 

 properties, has not been discovered thus far but progress is being 

 made. The importance of such a development is evident since it 

 M^ould decrease the labor and the investment in refrigeration equip- 

 ment as well as make it possible to purchase meat at periods of low 

 prices. 



Salmon carcass meal has proved somewhat more satisfactory in 

 practical feeding than seal carcass meal although both can be used. 

 White fish meal from which much of the bone has been excluded has 

 been found of sufficient value to justify the additional cost of this 

 special product. 



The primary function of the Cortland station has been to develop 

 a science of fish nutrition and to provide improved feeding prac- 

 tices for American hatcheries. Inevitably, however, diseases other 

 than nutritional ones arise in the course of such investigations. These 

 have been excluded when possible but some use has usually been 

 made of epidemics to discover possible interrelationships with the 

 nutrition. 



During the spring of 1937, the yearling and adult brook trout 

 developed ulcer disease. These were divided into groups and fed 

 various vitamin concentrates and specific chemical com):>ounds. Some 

 of the products fed were vitamin C, extract of pine needles, potassium 

 iodide, dried yeast, arsenious oxide, boric acid, borax, dinitrophenol, 

 thallium acetate, and sulfanilamide. This heterogeneous list rep- 

 resents specific selections in a rational attack but failure resulted 

 in every case. The last comjiound, sulfanilamide, was the only one 

 that afforded any hope of usefulness that would justify further 

 study. 



During the past year efforts have been continued to develop better 

 methods for chemical balance studies with trout. The aim of such 



