Februaet 12, 1904.] 



SCIENCE. 



249 



Gas-disease of Fishes.' This work, which 

 was carried on jointly with Professor Gor- 

 ham, was directed toward discovering the 

 cause of 'pop-eye' due to gas, and the 

 causes of mortality among fishes in the 

 local aquarium whether with or without 

 'pop-eye.' It was found that the sea 

 water from the supply pipes of the station, 

 when delivered below the surface of the 

 water in an aquarium, was fatal to most 

 species of fishes after a longer or shorter 

 time, Funduhis being most resistant; that 

 when the water delivered Avas first some- 

 what broken up, causing it to spatter or 

 spray, the mortality tended to lessen, and 

 'pop-eye' to decrease; that when the de- 

 aeration process was sufficiently complete, 

 the 'pop-eye' and the mortality were pre- 

 vented completely. 



By placing fishes (seup) under various 

 air pressures greater than the atmospheric, 

 in the same water which ordinarily pro- 

 duced 'pop-eye' and killed the fish, the 

 'pop-eye' and the mortality were found to 

 be checked, being inhibited altogether by a 

 pressure of between six and seven pounds 

 per square inch. 



Scup adjusted to surface pressure for one 

 week were as susceptible as those brought 

 directly from the fish traps, which had 

 probably come from somewhat deeper 

 water. Artificial reduction of air pres- 

 sure produced the same gaseous lesions as 

 those which had been shown by fishes in 

 the aquaria under the infiuence of the local 

 water supply, viz., 'pop-eye,' gas blebs, 

 death with free gas in the blood vessels, 

 according to the degree and the duration 

 of the reduction. Death occurred in a 

 few hours at a pressure reduced to less 

 than that of twenty inches of mercury. 



Determinations showed that the aqua- 

 rium water has a proportion of dissolved 

 gas considerably in excess of that from the 

 basin or harbor. This excess is believed 

 by the investigators to be caused by the 



hydrostatic pressure of the supply system, 

 in conjunction with leaks in the suction 

 pipe which admit air to the water imme- 

 diately prior to its being pumped to the 

 supply tank. This excess of gas in solution 

 consists of one or more of the constituents 

 of air. 



The immediate cause of death was usu- 

 ally found to be the presence of free gas 

 in the blood vessels. According to the in- 

 vestigators, this free gas is formed in the 

 following manner: The blood of fishes liv- 

 ing in this supersaturated water takes up, 

 while in the gill capillaries, more than the 

 usual amount of gases, thus reaching 

 nearly or quite to the saturation point. 

 These gases are, however, liberated as soon 

 as the blood becomes raised to a higher 

 temperature in the systematic circulation, 

 thus continually accumulating in the ves- 

 sels. 



Samuel Steen Maxwell, Ph.D., instx-uetor 

 in physiology. Harvard Medical School: 

 'Comparative Study of Muscular Tonus.' 

 The phenomena of muscular contraction 

 were studied in a somewhat wide range of 

 forms. Especial attention was given to 

 the occurrence of spontaneous or rhythmic 

 contractions in muscles or muscle groups 

 separated as completely as possible from 

 the influence of nervous tissues. Among 

 the forms investigated were Nereis, 

 Crepidula, Modiolus, Mytilus, Homarus, 

 Libinia, Limulus, Carcinus, Mnemiopsis 

 and Gonionemus. 



In order to retain the muscle alive for a 

 sufficient period of time, it seemed neces- 

 sary to find a solution which could be used 

 upon the tissues of marine animals in the 

 same way as the customary physiological 

 salt solution is used upon the tissues of 

 land animals, and considerable time was 

 devoted to experiments along this line. 



A full report of the experiments will 

 be published as soon as possible. 



