

INTERNAL SECRETIONS 367 



G. THE PITUITARY BODY 



On the basis of anatomical and embryological facts most authors assume a 

 close physiological relationship between the hypophysis cerebri i. e., anterior 

 part of the pituitary body and the thyroid gland. This supposition is supported 

 by the facts, to this extent at least, that hypertrophy of this structure has been 

 observed in animals after extirpation of the thyroid, and in men suffering from 

 myxoedema. A satisfactory explanation of this relationship has not yet been 

 found. 



Recently many experiments have been made on the effect of injecting extract 

 of the hypophysis into the circulation, and a distinct action upon the heart and 

 blood vessels has been obtained. According to Schafer and Vincent, we have 

 to do here with two different substances, which are distinguished chemically by 

 their solubility in alcohol and ether, one being soluble, the other not. 



The former brings about a very temporary fall in the arterial blood pressure. 

 The other increases the blood pressure, slows and strengthens the heart beat 

 and produces a marked diuresis. The effect is tolerably permanent, although it 

 becomes less and less with successive injections. From experiments on the iso- 

 lated heart or heart muscle it appears that this influence extends to the peripheral 

 end apparatus of the cardiac nerves. Other observations indicate that the extra- 

 cardial center also is stimulated (Cyon). The vasomotor nerves behave in the 

 same way : on the one hand the vessels contract after destruction of the medulla 

 (Oliver and Schafer) ; on the other, the vasoconstriction occurs if the extract 

 is injected into the brain vessels only (Cyon). In Cyon's opinion the effects of 

 an extract on the heart and on the vessels depends upon two different substances. 



Curiously enough the substances which produce this effect upon the circu- 

 lation, according to Howell, Schafer, and Vincent, are, for the most part at 

 least, not contained in the anterior glandular part of the pituitary body, but in 

 the posterior infundibular part. However, this section of the pituitary body 

 also contains glandular epithelial cells, which surround cavities filled with a 

 colloidal substance (Berkley). 



From results thus far before us no positive conclusion can be drawn as to 

 the normal working of the hypophysis. 1 It is conceivable that the substances 

 obtained by different methods from the gland are normally formed there and 

 are given off to the blood. But it is also possible that they represent products of 

 decomposition which are formed post mortem only, in the methods of extraction. 



A definite choice between these two possibilities is not yet possible, since 

 from the many conflicting statements as to the results of extirpation, we cannot 

 tell certainly whether any disturbances follow loss of the hypophysis alone. 



H. THE KIDNEYS 



Certain observed facts indicate that the kidneys not only remove different 

 products of decomposition from the body, but give off to the blood one or more 

 substances which are of service in the body. When the kidneys are removed 

 from an animal, or are rendered functionless in man, within a few days symp- 

 toms of severe uramic poisoning make their appearance. The most natural 

 assumption is that the symptoms are caused by the retention of the products 



1 Fischera has reported quite recently that castration of cocks, guinea pigs and rab- 

 bits produces a marked hyperplasia of the hypophysis. The change in the capon is very 

 sudden and can readily be recognized in microscopical sections of the part. Injection of 

 testicular extract just as quickly abolishes the hyperplasia or prevents it altogether. ED. 



