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



2. The Ordinary Phenomena of Rigor in Fish. 



The changes which take place before and during rigor will be best 

 illustrated by the following experiments : — 



(1.) Physiological Laboratory, Oxford, 4th February, 1887, 3 p.m. — A 

 large active perch (Perca fiuviatilis) was taken from the tank and laid 

 on the floor of the Laboratory, temperature 48° F. For about twenty 

 minutes the perch at irregular intervals was very active, but the move- 

 ments gradually diminished, and about thirty-five minutes after it left 

 the water, all movements had ceased and there was no response to 

 mechanical stimulation. When stimulated at 3.45 by induction 

 shocks, there was no response until the secondary coil indicated 

 15 cm.* The muscular irritability gradually diminished, and at 5.45 

 there was only a slight response at the break with the secondary coil 

 at cm. At 5.50 the lower jaw and gill-covers were nearly rigid, 

 and the irritability had quite gone in the muscles near the root of the 

 tail, the last to survive. At 6.0 the pectoral and dorsal fins were 

 rigid, and at 6.10 the rigor had extended as far as the pelvic fins. 

 At 6.15 the whole fish had passed into a pronounced rigor, the 

 mouth was open, the gill-covers projected outwards, all the fins were 

 extended, and owing to the shortening of the muscles of the left side, 

 the fish (which was 9 inches in length) was sufficiently curved to form 

 an arxLof a circle 30 inches in diameter. s , "While, the.._mu§cles remained 

 irritable, they were neutral or amphichroic, but as the rigor extended 

 from before backwards they became distinctly acid. 



As soon as the rigor had set in the perch was placed under a bell- 

 jar in a porcelain dish containing sufficient water to keep the skin 

 moist. At 10 p.m. the rigor was still well marked, but next morning 

 (5th February) at 10 a.m., the rigor had disappeared from the lower 

 jaw, gill-covers, and pectoral fins. When placed with the convex 

 side looking upwards, the lateral curvature of the trunk soon 

 gave way and at 12 noon the whole fish, except about 3 inches at the 

 tail end, was quite limp. 



At 10.30 a.m., the muscles in front of the dorsal fin were neutral, 

 those behind distinctly acid, at 12 noon the muscles of the anterior 

 half were slightly alkaline, those near the root of the tail were still 

 neutral. Numerous bacteria were found in the layer of muscles lying 

 around the body-cavity, and a few were found in the muscles under 

 the skin in front of the dorsal fin, but no bacteria could be discovered 

 either by direct observation or by cultivation in the muscles near the 

 root of the tail. 



On the 6th February putrid odours were discernible, all the 



* A single Daniell was used in the primary coil in the Oxford, and two Smees in 

 the Edinburgh experiments. 



