PHYSIOLOGICAL STUDIES OF THE CHINOOK SALMON. 



435 



As in the case of the marine salmon, it was found impossible to transport these fish 

 without considerable asphyxiation, and they did not revive as well as could be wished. 

 While the pressures given in Table I, below, are strong, still they must be considered 

 somewhat below the normal for the fish in its native waters. The heart beat is obvi- 

 ously far below the normal, a fact which is due to the failure of the ventricle to follow 

 .each contraction of the auricle. 



Table I. — Blood pressure from flu- ventral aorta of salmon taken f rom Suisun Bay at tin- mouth of tin 



Sacramt nin River. 



BLOOD PRESSURE IN SALMON FROM THE SPAWNING BEDS. 



Blood-pressure experiments were performed on some forty different salmon 

 taken from the McCloud River at Baird, Cal." Twenty-one of these experiments 

 were made in the summer of 1901 and the remaining- nineteen in 1902. The majority 

 of the fish used were young males or females that had been artificially spawned. A 

 few were old exhausted specimens, males and females that had come down the river 

 from the spawning beds above. Two or three were prune, large, unripe males and 

 females. The great intrinsic value for propagation purposes of these prime fish at 



t I II I I I 1 O I I I M I I I II I I I I t I I 



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I l I O I I I I I I I I I 



Fig. 1. — Experiment Aug. 20. 1902. Salmon. No. 207, female; Length, S23 millimeters. This tracing gives a normal blood pres- 

 sure from the ventral aorta. Maximal pressure. 75 millimeters of mercury; heart rate. 08 per minute; pulse pressure. 16 

 millimeters of mercury. In this and the following figures the tracings were recorded by means of a Ludwig's mercury 

 manometer. The time is in seconds and the time line represent the zero pressure. All figures are reduced one-half. 



the hatchery deters one from using more than are absolutely necessary for experi- 

 mental purposes. Figures 1 and 2 give typical ventral aortic blood-pressure tracings. 

 Table II represents the total set of blood-pressure measurements. The maximal 

 blood pressure, the heart rate, and the respiratory rates in all the blood-pressure 

 experiments are brought together in the table following for convenience in reference. 



aThe United States fish hatchery at Baird furnishes an ideal spot for the study of the salmon on the spawning beds. 

 An abundance of live specimens can be obtained at the very door of the hatchery, and the station is provided with the 

 necessary equipment for handling the fish. I wish here to thank especially the superintendent, Mr. G. H. Lambson, and 

 the accommodating hatchery force for numerous courtesies during the progress of the work. 



