I2/| 



ELEVENTH LECTURE. 



Fig. 115. — Colloid metamor- 

 phosis of the thyroid gland ; 

 a, gland-vesicle of the rabbit ; b, 

 commencing colloid metamor- 

 phosis of the calf. 



homogeneous firm mass, an obscure derivative of the albu- 

 minous bodies, the so-called colloid. In the interstitial con- 

 nective tissue we meet with a developed, 

 round-meshed reticulum of blood capil- 

 laries 0.02 to 0.023 mm - broad ; together 

 with these there is a widely extended 

 lymphatic canal-work. How far it 

 stretches, whether it finally circumvo- 

 lutes each cavity in a cap-like manner, 

 as Boechat recently asserted, requires 

 more accurate investigation. Previous 

 injection studies by myself and Pere- 

 meschko showed nothing of the kind. 



At a later period of life — and the 

 thyroid gland appears to grow old 

 early — this colloid substance seems to 

 increase more and more. The cavities 

 become distended, the small parietal 

 cells are more and more compressed, and with them the in- 

 terstitial connective tissue. In the further progress, these 

 cavities flow together, forming larger ones. 



It is assumed of the thyroid gland, like the apophysis cere- 

 bri and the suprarenal capsule entirely hypothetically, that 

 it removes matters from the blood which, when the same are 

 further metamorphosed, either indirectly or directly, are 

 afterwards restored to the central fluid of the organism. 

 Hence the denomination of the " blood-vascular glands," a 

 proof of our ignorance at that time. 



Just as obscure are the suprarenal capsules, glandular suc- 

 centuriales, structures which once at an earlier foetal period 

 possessed an immense size, and subsequently remained more 

 and more behind. 



Here, also, we meet with a double mass, a cortical and a 

 medullary layer. The former appears to have a radiated dis- 

 position, brownish, reddish or yellowish. The latter, much 

 softer, is usually more transparent, grayish, red or yellowish. 

 The least resistance is possessed by a border zone which in 



