149 



they very much resemble the muscular fibres of the lymphatic hearts 

 of the frog; but in none did the author detect an unequivocal ap- 

 pearance of transverse marking. The fibres of the middle coat of 

 the artery are not so pale looking, are clearer, and exhibit a more 

 strongly marked contour. 



2. " Some Observations on the Ova of the Salmonidse." By John 

 Davy, M.D., F.R.S. Lond. and Ed., Inspector-General of Army 

 Hospitals, &c. Received November 20, 1851. 



The author prefaces his observations by a quotation from the 

 work of M. Vogt on the Embryology of the Salmonidae, in w^hich 

 a remarkable property of the vitellus is described, viz. its coagula- 

 tion by admixture with water. 



This inquirer's experiments were made chiefly on the ova of the 

 Palee {Coregonus Palaa, Cuv.) ; the author's mostly on the ova of 

 the Charr (Salmo umbla). After giving a description of the mature 

 eggs of this fish, he details the trials instituted by him : — 1st, on the 

 action of water, showing its coagulating effect, except when added 

 in very minute quantity. 2ndly, on the action of heat ; how that a 

 dry heat, even so high as that of 212° Fahr., occasions the contrac- 

 tion of the vitellus from evaporation, but not its coagulation, an 

 effect even not produced by steam of the same temperature, but 

 which is occasioned by boiling in water, owing, it is inferred, to an 

 admixture of water. 3rdly, on the action of alkalies and salts ; how 

 these, such as potassa, ammonia and their sesquicarbonates in solu- 

 tion, nitre, acetate of lead, common salt and others, when of 

 moderate strength, not only do not coagulate the vitellus, but have 

 the property of dissolving a certain portion of coagulum, and coagu- 

 late it only when very much diluted. 4thly, on the action of acids 

 and some other agents ; how the vegetable acids tried, as the tar- 

 taric, oxalic, acetic, whether strong or dilute, do not coagulate the 

 vitelline fluid, but dissolve its coagulum ; how the strong sulphuric 

 and muriatic acids inspissate it, the weak coagulating it ; and fur- 

 ther, how it is coagulated by the nitric acid, by corrosive sublimate 

 and by alcohol, but not by iodine. 



The inference from the experiments drawn by the author is, that 

 the vitellus of the Charr and of the eggs of the other Salmonidse is 

 distinct in its properties, both from the albumen and yolk of the eggs 

 of birds. He conjectures from analogy that the ova of other species 

 of osseous fishes will be found to be similar; but not so those of the 

 cartilaginous fishes. According to the observations he has made, the 

 yolk of the eggs of fishes of this order, whether they possess a white, 

 as in the instance of the oviparous ; or are destitute of a white, as in 

 that of the viviparous, resembles in its general character that of the 

 egg of birds : but he doubts that the white of the former will be 

 found analogous to that of the albumen ovi of birds, at least in its 

 chemical qualities ; having in one instance, that of the egg of the 

 Sqmlus Catulus, found it to be, whilst transparent and viscid, neither 

 coagulated by heat nor by nitric acid. 



In conclusion, he suggests that the coagulation of the ova of the 

 Proceedings of the Royal Society. Vol. VI, No, 86. ii 



