118 FATS 



relations of the two glands tend to confirm, that the active principle 

 of the posterior lobe is derived by partial decomposition from that of 

 the anterior lobe. 



Tethelin, in very small dosages administered by mouth, has a 

 remarkable effect upon the growth of animals, consisting in the main 

 of an initial retardation followed by a notable acceleration of growth. 

 These phenomena will fall under fuller consideration in a later chapter. 

 When administered locally in aqueous solution or incorporated with 

 lanoline and applied as a salve it very markedly accelerates the repair 

 of slowly healing lesions of the skin, such for example as various 

 ulcers. The effects of tethelin upon growth almost exactly reproduce 

 those of the whole anterior lobe tissue, and it is inferred that tethelin 

 is the active principle, the absence or superabundance of which is 

 responsible for the remarkable clinical manifestations of hyperactivity 

 (gigantism and acromegaly) of the pituitary gland. 



Tethelin in aqueous solution has no effect upon the uterus, and 

 only causes in very large dosages a slight transient fall in blood pressure 

 when injected intravenously in animals. After acidifying the solution 

 (or rendering alkaline), heating for a brief period to nearly boiling- 

 point and then cooling and neutralizing, however, the solution has a 

 powerful effect in causing tonic contractions of the uterus similar to 

 those caused by extracts of the posterior lobe, and when injected 

 intravenously causes the characteristic rise in blood pressure which is 

 brought about by small doses of posterior lobe extract (Pituitrin). 



In the tissues of the brain we find a complex substance or series 

 of substances which arise by combination of phospholipins with the 

 cerebrosides which are glucosides yielding galactose on hydrolysis. 

 This substance, Protagon, may be obtained by extracting dehydrated 

 brain-tissue (dehydrated by acetone) with 85 per cent, alcohol, and 

 cooling to zero when the protagon in impure form is precipitated. On 

 partial hydrolysis it yields sphingomyelin (see p. 116) and cerebrosides 

 (see p. 91). 



Protagon when dry forms a fine white powder, it dissolves in 85 

 per cent, alcohol at 45 C., but on cooling is precipitated in groups of 

 small acicular crystals. It is difficultly soluble in cold alcohol or ether, 

 but dissolves in warm ether. It dissolves in methyl alcohol contain- 

 ing chloroform but, on standing, this solution decomposes and a 

 cerebroside, Phrenosin is deposited. In water protagon swells up and 

 forms a pasty mass which dissolves in excess of water, forming an 

 opalescent solution. Solutions of protagon in pyridin are dextro- 

 rotatory, but on standing they decompose, depositing sphingomyelin, 

 and become levorotatory. 



We are not certain whether protagon is a chemical individual or 

 not. The composition as reported by different observers, varies 

 very considerably, and yet preparations have been obtained which 

 failed to alter in composition or optical rotation of their solutions after 

 repeated resolution and recrystallization. 



