450 Dr. J. C. Ewart. On Rigor Mortis in Fish, [June 16 r 



trout about 10 inches in length the temperature during life was- 

 10 "15° C, the temperature of the water being 9° C, and the air 9'3° C. 

 After death the temperature fell to 9'5°, but as soon as the rigor had 

 set in, the temperature of the muscles rose rapidly, reaching when the- 

 rigor was all but completed 10'3° C. Ten minutes after the rigor had 

 been completed the temperature was 10'2°, and it gradually fell until 

 it reached 9° C, forty-five minutes after the maximum had been 

 reached. In this fish rigor began to disappear two hours after death, 

 and as the rigidity vanished the temperature again rose, being 10° C. 

 three hours after death, 10"05° when the rigor, four hours after death r 

 had vanished from the anterior third of the fish, and 10"03° when only 

 the muscles of the tail continued rigid, when the fish became quite- 

 limp ; six hours after death the temperature was again 9° C. As 

 putrefaction proceeded the temperature again rose to 10° 0., and it 

 varied between 9*5° C. and 10° C. for two days, after which it was 

 the same as the temperature of the laboratory. The acidity increased 

 as the rigor came on, and then gradually diminished until the muscles- 

 were neutral. As putrefaction advanced the tissues became decidedly 

 alkaline. 



The rigor is least persistent in fish which die in an exhausted con- 

 dition at a high temperature. If an exhausted trout is placed 

 immediately after death in water at a temperature of 35° C, rigor 

 appears in from 3 to 10 minutes and disappears in from 15 to 30' 

 minutes, i.e., at the most 40 minutes after death. 



If a trout is killed and pithed and then introduced into water at a 

 temperature of 35° C, the rigor appears in from 10 to 15 minutes, 

 and persists from 50 minutes to 1 hour. In a fish treated in the same 

 way at a temperature of 25° C, rigor appears in from 60 to 65 minutes, 

 and persists for 2^ to 3 hours ; while a similar trout placed in water 

 at 15° C. does not begin to stiffen for 5 hours, and the rigor may only 

 be completed 7 hours after death, and begin to pass off about 20 hours^ 

 after death. The nervous system has doubtless considerable influence 

 in determining the length of the rigor, as it has in deciding its time 

 of setting in. If an active trout (A) is carefully captured and allowed 

 to die in the landing-net, which when undisturbed it usually does 

 without a struggle ; and if when all signs of life in (A) have vanished, 

 a second trout (B) is secured and at once killed and the brain and 

 spinal cord destroyed ; in (A) the rigor may begin to disappear 2 hours 

 after it has been completed, and may only last altogether 7 or 8 hours, 

 while in (B) it may last at least 24 hours. When the brain only is 

 destroyed it disappears from 1 to 1^ hours sooner, the temperature 

 being from 9—10° C. 



The difference of the duration of the rigor in fish which are 

 allowed to die and in fish which are knocked on the head or have both 

 brain and spinal cord destroyed is well marked at all temperatures above 



