312 INTERNAL SECRETION 



Quite recently, however, Gemelli expressed the view that the 

 chromophile and chromophobe cells represent two different cell 

 varieties. Pirrone, Guerini, Launois, Thaon and Joris adopt 

 Benda's view, with this modification that they regard colloid as 

 the end product of the secretory process. 



The amorphous substance resembling the colloid of the 

 thyroid is regarded by Benda, Gemelli and others as the product 

 of degeneration. Erdheim regards it as rudimentary and re- 

 miniscent of a time when the organ possessed an external secretory 

 function. By many authors, particularly those of the French 

 school, the colloid substance is regarded as the product of normal 

 secretion. 



Of the chemical nature of this colloid, all that is known is 

 that it is insoluble in water, alcohol and ether; that it does not 

 yield gelatine after boiling; and that, unlike mucin, it swells in 

 acetic "acid and afterwards dissolves. It has been identified with 

 the colloid substance of the thyroid and this is confirmed by the 

 discovery of iodine in the hypophysis. 



The colloid substance is present in the hypophysis of the 

 human embryo at three and a half months; in adults, it is found 

 in the cell columns and is particularly abundant in the vesicles in 

 the neighbourhood of the hilus, and in the blood-vessels. In 

 addition to a strongly coloured, eosinophile, homogeneous colloid, 

 the hypophysis, like the thyroid, also contains a less homo- 

 geneous, granulated, basophile substance resembling coagulated 

 albumin. The colour differentiation of the colloid substance 

 depends upon the different granulation of the acido- and baso- 

 phile cells. 



The presence of the colloid substance between the cells, in 

 the vesicles, and in the lumen of the capillaries is regarded as 

 proof of its excretion by way of the blood-stream. Thaon showed 

 the manner in which the secretion is excreted in series of sections 

 from hypophyses which showed signs of hypertrophy. In addi- 

 tion to colloid, he found fat granules between the cells and in the 

 capillaries; he was unable to demonstrate the presence of lym- 

 phatics in the hypophysis. According to Thaon, the secretion is 

 eliminated from the hypophysis in two ways; one, through the 

 cell base into the blood-vessel with which it is in contact; the 

 other, through the opposite cell wall into the lumen of a vesicle, 

 where present. 



The presence of colloid in the vesicles may be considered to 

 be evidence of the deposition of this substance ; thus it is possible 

 to regard the hypophysis as a storage gland, similar in character 

 to the thyroid apparatus. Thaon believes that the physiologically 

 active substance of the posterior lobe, is merely the secretory 

 substance elaborated by the anterior lobe, which accumulates in 

 the vesicles in the neighbourhood of the hilus. The method of 

 preparing pituitary extract does not permit of any separation of 



