INTRODUCTION 41 



adapted to the destruction of small organs, such as the parathyroids. The 

 writer found it an excellent method of destroying the suprarenals and 

 other en doer in glands in such small animals as newly-born guinea-pigs. 

 It is both more expeditious and less likely to result in hemorrhage than are 

 cutting operation. 



Infarction. Bland infarcts can be produced by injecting fine suspen- 

 sions of inert insoluble material into the arteries leading to the different 

 glands. Tobacco seed or lycopodium spores are most commonly em- 

 ployed. This process involves comparatively little trauma and can be reg- 

 ulated to some extent to produce various grades of deficiency. It is a 

 method, however, somewhat difficult to control with any satisfactory degree 

 of accuracy, and so far has not led to any very striking results. 



Ligation of Blood Vessels. Ligating the blood vessels of a given organ 

 in order to decrease its function is employed in both clinical and experi- 

 mental practice. It is a well-known method of treating exophthalmic 

 goiter in patients who are in too precarious a condition to undergo thyroid- 

 ectomy. For experimental work the method is in most cases unreliable. 

 In cases in which it is desired completely to occlude the circulation small 

 vessels may bo left untied and these quickly enlarge ; or capillaries from 

 the surrounding tissue may soon grow into the ischemic area and vascular- 

 ize it, thus permitting the peripheral parts of the gland to hypertrophy 

 and continue to function. In case of the suprarenal glands, the loss of 

 which is rapidly fatal, ligation of the blood vessels seems to be essentially 

 equivalent to extirpation. When complete occlusion of the circulation of a 

 given gland is desired this may often be expeditiously accomplished by 

 passing beneath the gland in situ a suitable needle carrying two ligatures. 

 If one of these is utilized to form by constriction a pedicle beneath the 

 gland on each side, and is then drawn tight, complete isolation is neces- 

 sarily secured. 



Interstitial Injury. Of the various methods of destroying the tissues 

 by the use of injurious materials, the injection of hot water is probably the 

 best. The method is relatively safe, no harm being done if the fluid pene- 

 trates a blood vessel, whereas in case of chloroform, chromic acid or 

 other escharotics they are likely to escape into the circulation and produce 

 serious or even fatal injury. The method has been relatively little used 

 in experimental investigations, although it is well known as a method of 

 treating exophthalmic goiter. Of recent years injections of boiling water 

 or of quinin and urea hydrochlorid have been most frequently employed. 

 An obvious disadvantage of the injection method is the difficulty of 

 control. 



Specific Cytolysis. After the discovery of the possibility of inducing 

 an increase in the cytolytic power of the blood by the injection of specific 

 antigenic cells, a hope was entertained that the method would prove 

 valuable in endocrin research. It has been reported that if an animal 



