28 



Dr John Davy on the Blood. 



7. Of the Sea-Trout. — When in Lewes of the Orkney 

 islands, in the beginning of August, I availed myself of the 

 capture of some fish of this kind in the sea with the net to 

 examine the blood. About half an ounce was collected 

 from three fish by cutting the gills the instant they were 

 taken out of the water. After fifteen minutes' exposure, on 

 evaporating the acid, a distinct trace of muriate of ammonia 

 was observed, and rather more on a second trial after four 

 hours' exposure. The coagulum was soft and dark. 



8. Of the Toad. — This trial was made in July. The 

 toad was of ordinary size, and vigorous, as it commonly is in 

 this month. Though the quantity of blood was small, it 

 afforded a distinct trace of ammonia after an hour's ex- 

 posure. As the blood was obtained by decapitation, it was 

 a mixture of venous and arterial.* 



9. Of the Fluid of the A llantoid of the Egg of the Common 

 Fowl. — In this fluid, when the foetal chick had nearly 

 reached its full time, I have detected ammonia. The fluid 

 was of sp. grav. 1016, of alkaline reaction ; on evaporation 

 after the addition of hydrochloric acid, it yielded some 

 minute crystals of muriate of ammonia. In this stage of 

 existence the chick may be considered as differing but 

 little from the batrachian, the respiratory function being of 

 no greater activity than sufiices apparently for the organic 

 clianges essential to development, and nowise sufiicient to 

 preserve the temperature essential to the life of the foetus. f 



What are the conclusions to be drawn from these re- 

 sults ? 1. Do they not all tend to confirm the inference 

 that the congulation of the blood is not owing to the escape 



third day, the serum of the calf's blood was still colourless ; that of the horse's 

 only very slightly coloured. 



* When stooping over the toad, a nauseous smell was perceived, and an acrid 

 taste in the pharynx, followed by slight headache and malaise, which at the 

 time I fancied might be owing to vapour from the body of the reptile. The 

 cutaneous glandular structure was in an active state, and distended with its 

 peculiar acrid fluid. 



t It is very remarkable how rapidly the temperature of the young bird 

 rises when its active respiration is established. The following is an ex- 

 ample : — The temperature of a gosling, in process of hatching, just after the 

 end of tlie egg had been partially broken, was 94° ; two hours later it had 

 rieen to 104° ; after other two hours to 109° ; then its head was out of the 

 shell, and the young bird was making muscular efforts to extricate the body. 



