TWENTY MONTHS OF STARVATION IN AMIA CALVA. 455 



be no question but that it lives upon the large aquatic animals. 

 The effects of this habit is that the gill-rakers are short, blunt 

 processes and between each there is a short space. This means 

 that they are not effective straining organs for minute particles 

 of food. Bacteria and diatomes easily pass between them and 

 out through the gills into the surrounding water. The structure 

 of the gills alone is sufficient to answer the question whether or 

 not Amia used the microorganisms as food. I believe that the 

 amount of food secured by these fish from the water is negligible. 

 The question which Putter, 1 Moore and others have raised in 

 regard to the role that organic compounds (other than those 

 ingested) play in nourishing animals receives a negative answer 

 in the case of Amia in so far as these experiments are related to 

 the utilization of organic compounds in solution in the water. 



COLOR CHANGES. 



As the breeding season approached, the green color of this 

 female took on a brighter tint that was in sharp contrast to the 

 usual dull color. By the middle of April, this intensifying of the 

 color reached its height and gradually declined during the next 

 three weeks until the regular dull shades were again assumed. 

 On the second return of spring, a similar color change was 

 indulged in. This was surprising as I was accustomed to think 

 of these secondary sexual changes as following a vigorous, well- 

 fed condition. Here the reverse is true as the animal was so 

 emaciated as to be hardly able to swim and then in a very feeble 

 manner. It would seem as if this secondary sexual coloration 

 in Amia was a rhythmical process recurring at the period of the 

 breeding season irrespective of bodily vigor. 



BLOOD. 



On October 8, 1913, one Amia just received from Alexander 

 Nielson was etherized and the blood immediately studied. The 



1 Putter, A., 1907, "Die Ernahrung der Wassertiere," Zeit. f. allg. Physiol., 7, 

 Hf. 2 and 3, pp. 283-320. 1909, "Die Ernahrung der Wassertiere und der Stoff- 

 haushalt der Gewasser," pp. 1-168, Jena, Vergl. G. Fisher. Moore, Benjamin, 

 Edward D. Edie, Edward Whiteley, W. J. Dakin, 1912, "The Nutrition and 

 Metabolism of Marine Animals in Relation to (a) Dissolved Organic Matter, and 

 (b) Particulate Organic Matter of Sea-water," Biochem. Jour., vol. 6, pp. 255-297. 



