534 ANIMAL SUBSTANCES 



Adrenalin is the most powerful haemostatic known. By sub- 

 cutaneous injection the blood-vessels are locally constricted so as 

 to render minor surgical operations almost bloodless. It is similarly 

 used to arrest postpartum and other haemorrhages. 



Adrenalin is laevo-dihydroxyphenyl-ethanol-methylamine (laevo- 

 methylamino-ethanol-catechol) , C 6 H 3 (OH) gCHOHCHaNHCHg, very 

 slightly soluble in water, almost insoluble in alcohol, ether and 

 chloroform ; a dilute acid solution gives with a trace of ferric chloride 

 an emerald green colour which is changed to purple or carmine by 

 the cautious addition of a dilute solution of sodium hydroxide. 



THYROID GLAND 

 (Glandulae Thyroidei) 



Source, &c. The official thyroid gland is obtained from the sheep, 

 Ovis aries, Linne (N.O. Ungulata). 



Description. The thyroid gland is a highly vascular organ consisting 

 of two almond-shaped lobes generally united towards their lower ends 

 by a narrow bridge of tissue called the isthmus and forming a rounded 

 projection on the trachea. It is distinguished from the surrounding 

 tissue by its dark red colour and firm, coarsely granulated texture. 

 Embedded in its substance are multitudes of closed vesicles containing 

 a yellow glairy fluid termed colloid. This secretion contains the active 

 constituent of the gland which probably passes into the system through 

 the lymphatics. Each lobe of the fresh sheep's thyroid weighs about 

 2 grammes. 



The lobes are usually removed separately, freed from surrounding 

 fat and connective tissue, sliced or minced, and rapidly dried in a 

 current of warm air at 30 to 40. When sufficiently dry they are 

 reduced to a coarse powder and the remaining fat removed by 

 petroleum spirit. They are finally completely dried in a desiccator. 

 Glands that are abnormal in size, or that exhibit cysts containing 

 fatty matter when cut, should be rejected. The dry thyroid thus 

 produced is a dull brown hygroscopic powder with a slight odour 

 free from putresence. 



Constituents. The active constituent appears to be a proteid 

 body, thyreoglobulin, which can be dissolved out by a weak solution 

 of sodium chloride and precipitated by the addition of ammonium 

 sulphate. This substance contains uniformly 1-6 per cent, of iodine 

 but no phosphorus. Boiled with dilute sulphuric acid it yields 

 iodothyrin (thyroiodin) which contains from 9 to 14 per cent, of iodine, 

 the constituent containing the iodine being apparently resistant to 

 heat. Iodothyrin has also been supposed to be the active constituent. 

 Fresh thyroids yield about 30 per cent, of dry, containing an average 

 of 0-34 per cent, of iodine. 



