Katharine A. Brownell

Some Blood Constituents of the Normal Skate

IN PREPARATION for a study of the chemical changes produced by interrenalectomy in the skate we needed to know the values for normal animals. Smith (I929) has published normal values for electrolytes and urea in Raja laevis and R. diaphenes. At Woods Hole the most satisfactory animal for our purpose was the common skate, R. erinacea, because it was plentiful and it could be interrenalectomized without too much difficulty. Little or no data have been published on the electrolytes and urea in this species. Moreover, too little attention to the effect of inanition has been given. Kisch (1930) has shown that starvation causes a fall in blood urea, but he did not determine the electrolytes. We studied the range of variation in a large number of animals in both blood and perivisceral fluid. Then the effects of inanition and feeding were followed after it was found that plasma sodium rose with the fall in blood urea. Blood sugar and volumes per cent of erythrocytes were also determined.

LIPIDS IN THE LOCOMOTOR MUSCLES OF BIRDS

Fat content in locomotor muscles is an important source of energy, especially during sustained activity (George and Jyoti, 1957). The amount of such fat varies with different species, but whether this depends upon the use made of these muscles or other factors is uncertain. George and Naik (1960) reported values for the pectoralis major of birds ranging from 2.18 to 6.35 per cent in 18 species. Hoping to throw more light on this question, we have conducted the present investigation. A comparative study of the weights of the locomotor muscles gave us the opportunity to determine the fat or lipid content of the muscles in a large number of species of birds. Our study included muscles of the lower extremities as well as the pectoralis. We have determined muscle lipids in 104 species representing 42 families.