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



As in warm-blooded animals which die before maturity is reached 

 from wasting diseases, the rigor soon appears and as rapidly goes, so 

 in young fish which have been living in confinement, the rigor is 

 often weak and evanescent. 



For example, a young roach about 6 inches in length, which for 

 some hours had barely managed to survive was killed, and, though 

 carefully watched, it was impossible to detect any rigor, and equally 

 impossible fifteen minutes after death to obtain any response from 

 electric stimulation with the secondary coil at zero. Again, as in a 

 " hunted hare " the rigor sets in rapidly and is of short duration, so 

 it is in a long " played " fish. Gn April 14th a trout was chased for 

 nearly half an hour before it was landed. About 20 minutes after it 

 was taken from the water, even although the brain was destroyed 

 immediately after death, the muscular irritability had disappeared, 

 and the rigor was complete before 30 minutes had elapsed with the 

 temperature at 9'5° C. Under ordinary conditions, if an active two- 

 year-old trout ($. levenensis) about 9 inches in length is taken from 

 the water and left in the landing net, it usually lies perfectly still, 

 only giving an occasional wriggle. During the first few minutes the 

 breathing movements are performed, but as soon as the fish realises 

 fully it is out of the water, the mouth and gill-covers are tightly 

 closed — an instinct which fish display, whereby they better their chance 

 of surviving until they again perchance reach their native element. 

 In from 20 to 30 minutes, probably owing to the muscles being ex- 

 hausted, the mouth is opened and the gill-covers are widely extended, 

 and in a few minutes later (5 — 10) the fish dies. If it dies in about 

 25 minutes, the- muscles will respond to mechanical stimulation 

 10 minutes after death, and 60 minutes after death all the muscles 

 will respond freely to electrical stimulation with the secondary coil 

 at 15 cm. Gradually the muscles from before backwards lose their 

 irritability, and \\ hours after death, though the muscles near the 

 tail still respond with the secondary coil at 15 cm., the muscles of the 

 lower jaw will only respond when the indicator is at zero, and 

 2 hours after death only the muscles of the posterior half of the trunk 

 retain their irritability. At 2J hours after death even the caudal 

 muscles require the secondary coil at 12 cm. ; 10 minutes later at 

 8 cm., and in 15 to 20 minutes more (about 3 hours after death) only 

 a faint response is obtained with the secondary coil at zero. Two 

 hours after death — before muscular irritability has gone from the 

 caudal muscles — the muscles of the jaw become rigid and the stiffen- 

 ing extends backwards, overtaking the gill-covers, the pectoral, 

 dorsal, and pelvic fins and one myotome after, until the rigor is 

 complete. 



The time required is never the same, but on an average the rigor 

 is accomplished in a trout allowed to die in a landing net, and 



