I 



PAEASITES OF THE SALMON OF THE TAT. 147 



any " animalcules " introduced from without ; yet in few or none 

 did such occur, cellulo-grauular matter and oil-glohules alone 

 appearing. In ten instances only did remnants of fishes occur, 

 and in all these nothing remained but vertebral columns, cranial 

 and other bones, with the denser tissues, as the lens, &c. The 

 number of bones in several cases showed that the animals had en- 

 joyed a most ample repast, since they belonged to fishes from 8 

 to 10 inches in length — of what species I have not been as yet able 

 to determine. Some pieces of cartilage, skin, and pigment-cells 

 seemed to belong to smelts, but most of the vertebrae belonged to 

 larger fishes. The other kinds of food found in the stomach con- 

 sisted of fragments of small freshwater Crustacea with a portion 

 of a shrimp in one or two fishes, and an occasional piece of in- 

 sect-cuticle. 



The duodenum is generally supplied in abundance with a less 

 cohesive mucus of an orange tinge, and which is continued along 

 the intestine. A constant accompaniment of this mucus in almost 

 all fishes is a number of whitish or yellowish masses, extending far 

 down the gut as a fragile knotted cord surrounded by the mucus — 

 in some instances nearly to the anus. When a small portion of 

 the white substance is put between glasses, it is gritty, and is 

 found to consist of a vast number of calcareous crystals like those 

 of the triple phosphate. They are quite unaflected by ether, but 

 effervesce much and disappear on the addition of hydrochloric 

 acid. Some of the larger crystals showed roughnesses on their 

 svu-faces, as if smaller crystals adhered or had adhered to form com- 

 pound masses ; others had a somewhat radiate arrangement of the 

 constituent crystals. They occiu'red in all portions of the intes- 

 tine from the pylorus downwards, but not in the pyloric caeca, and 

 appeared in the fasting as well as in the full-fed fish. The mucus 

 which more immediately surrounded them had a fibro-granular 

 aspect. The exact origin of these crystals is an interesting ques- 

 tion. So constantly were they present imder all conditions as 

 regards food, that they could not have been much influenced by 

 the varying state of the latter. The intestinal surface being an 

 eliminating as well as a secreting surface, we may conclude that 

 these crystals had their origin in fluids produced by the mucous 

 membrane. The skeleton of this fish being of small specific gra- 

 vity and deficient in earthy matter, it may be that the excessive 

 elimination of salts keeps down the specific gravity ; or again, 

 the circulating fluid by this means may so adapt the bones to the 

 varying density of the salt and fresh water that their specific 



