126 



pressure, be made to exude from the cell in refractive 

 globules. In specimens hardened in alcohol, this clear 

 secretion appears as a granular mass, occupying the 

 greater portion of the cell. It stains faintly with 

 haematein, and shows under high powers a coarse 

 reticulum and isolated globules, an appearance pro- 

 bably due to the precipitation or coagulation of the 

 secretion by the alcohol. 



The protoplasm of the cell occupies, in the fully- 

 matured gland, only the extreme periphery, and the 

 nucleus, which is much degenerated, is pushed to the 

 outer portion of the cell, and usually lies in the angular 

 interval left at the base of two or more contiguous 

 cells. 



The Clear or Colloid-like Type. Of this type 

 there is but a single acinus upon either side, which 

 usually lies between the two acini of granular type 

 (Fig. 46). 



In the fresh gland the cell outlines are not so 

 distinct as in the granular type, and the secretion, 

 when extended by pressure, is much less refractive. 

 In alcohol-hardened specimens, the acinar cells contain 

 a large mass of clear, homogeneous secretion which, 

 as in the last-mentioned type, fills almost the entire 

 cell, and pushes the protoplasm and nucleus to the 

 periphery. 



In the clear type, however, the protoplasm is 

 always in greater amount than is the case with the 

 granular type, and the nucleus never becomes so 

 greatly degenerated. The clear, homogeneous secre- 

 tion stains readily with haematein, and may even stain 

 quite deeply. With Heidenhain's haematoxylin it 

 frequently becomes 'almost black. It resembles very 

 much in appearance colloid substance as it is seen in 

 the mammalian thyroid. 



