14 



U. S. BUREAU OF FISHERIES. 



THE PADDLEFISH. 



The study of the natural history and artificial propagation of the 

 paddlefish in Bayou Pierre at Westdale, La., was continued by 

 Dr. A. D. Howard, scientific assistant, with the cooperation of the 

 Louisiana Conservation Conunission. During March good catches 

 of egg-bearing females and sufficiently ripe males were obtained, 

 but no females were ripe enough to allow of fertilization of eggs. 

 Late in the month heavy rains flooded the Eed Kiver and Bayou 

 Pierre and prevented the capture of fish in sufficient numbers to 

 continue the investigation. 



There are few added data regarding the breeding grounds of the 

 fish and the time and manner of spawning. Some information of 

 minor importance was obtained regarding certain habits of the 

 species. Bottoms suspected of being the breeding grounds of the 

 paddlefish were dredged for the purpose of obtaining eggs, but 

 without success. 



POISONOUS ACTION OF GAR EOE. 



In a previous year experimental attempts to produce caviar of gar 

 roe were made by Prof. C. W. Greene, temporary investigator. Out 

 of this work it developed that the pigment in the gar roe is not a 

 melanin as in the sturgeon roe, but a form of pigment that changes 

 color under various chemical treatments of the roe. The pigment 

 color is changed to an orange red on boiling the gar eggs, on treat- 

 ment with alcohol or ether, and on salting. This changes the com- 

 mercial quality of the product and gives easy methods for detecting 

 the adulteration of sturgeon roe by gar roe. 



The important observation, however, was the demonstration of an 

 active physiological principle of a toxic nature present in gar roe. 

 It is apparently this principle that gives the unpleasant acrid taste 

 to gar-roe caviar. When tested biologically by the method of feeding 

 the natural product the following points were made: (1) Gar roe is 

 poisonous to the chicken and to the rat; (2) it paralyzes the neuro- 

 muscular mechanism of the chicken crop; (3) it produces in the rat 

 an intestinal irritation with active diarrhea. 



During the summer of 1920 a series of experiments were made to 

 chemically separate and biologically test the unknown toxic sub- 

 stance. It was shown that (1) extracts in boiling water free from 

 coagulable protein and (2) similar alcoholic extracts contained an 

 active principle toxic to the heart of the frog; (3) globulin fractions 

 made by the method of salting out, centrifuging, and purifying by 

 dialysis were sharply toxic to the heart ; (4) the globulin fractions fed 

 to a young rat produced extreme diarrhea and death in about 20 

 hours, effects comparable to feeding the entire fresh ovary; (5) the 

 effect on the chicken's crop was positively toxic; (6) not only was the 

 crop paralyzed but an acute diarrhea occurred in the chicken through 

 some alimentary canal poisoning; (7) these effects also occurred after 

 feeding the purified globulin. 



Attempts to isolate and identify the individual chemicals, of which 

 at least two classes are present, have thus far not been brought to a 

 successful issue. Further experiments are planned. 



