40 K G. HOSKmS 



either man or animal. Nothing approaching experimental acromegaly 

 from pituitar^ administration has ever been reported. 



Depression of Hormones. Several methods of creating endocrin gland 

 deficiencies have been employed. Some of these are surgical extirpation, 

 producing bland infarcts in the glands, ligating all or part of the blood 

 vessels leading to or from the structures, injecting boiling water or injuri- 

 ous chemicals into the organs in question, or the injection of specific 

 cytolytic sera with a view to causing selective destruction of particular 

 endocrin cells. 



Gland Extirpations. The most common method of creating a func- 

 tional deficiency is the obvious one of removing all or a portion of the gland 

 in question. With the development of modern surgical technique this 

 method has come to have the utmost importance. The earlier investigators, 

 however, had little confidence in results derived from this type of experi- 

 ments. Schiff s early observations, for instance, on the effects of thyroid 

 extirpation were received with little favor, being commonly ascribed 

 merely to suppuration or to the injury of important nerves. The method 

 is particularly adapted to investigations of the problem as to which endo- 

 crin glands are essential to life. But even in such investigations, con- 

 cordant results have not in all instances as yet been reached. For example, 

 Gushing maintains that complete removal of the pituitary gland is inev- 

 itably fatal, while Asclmer, another skilled scientist, is equally sure that 

 animals may survive the operation. One maintains that death following 

 extirpation of the gland is due to incidental trauma or hemorrhage the 

 other that survival when it occurs is to be ascribed to bits of gland left 

 behind in the operation. That small residual fragments may survive and 

 hypertrophy is well known. An important complicating factor in many 

 cases is the existence of small masses of aberrant tissue lying at some 

 distance from the main gland. Accessory thyroids may be found any- 

 where along the trachea. Outlying suprarenal tissue is not uncommon, 

 along the course of the aorta and even as far away from the gland proper 

 as the epididymus. Parathyroids may occur in various parts of the neck 

 as well as in the thymus. In case of the guinea-pig, at any rate, Park has 

 imind that detached bits of thymus tissue are so common as to render 

 total extirpation of the gland, such as has frequently been reported in this 

 animal quite out of the question. The possible existence of these aberrant 

 structures in any given animal introduces an unavoidable element of un- 

 certainty. Xor will a careful autopsy in all cases determine whether the 

 object of the experiment has been attained. Unless complete serial secre- 

 tirns of all possihle tissues that might contain accessory glands are studied, 

 such may easily escape detection. In many instances such complete study 

 is obviously impracticable. 



In ii'land ^extirpations the actual or the electrocautery has in some 

 instances, distinct advantages over scalpel or scissors. It is' especially well 



