134 



TWELFTH LECTURE. 



called caseine. Their size varies between 0.003 to 0.009 mm. 

 The gland cells should now, with a far more energetic secre- 

 tion in the acinus, have been early destroyed. A different 

 view might, however, be entertained. The membraneless 

 cells may have thrown out the elaborated secretion, as the 

 crater of the volcano does the lava — -only the cells, like the 

 volcano, may persist. I regard this as indeed very plausible. 

 We have just spoken of probably the most perishable gland 

 elements, immediately after the discussion of more permanent 

 elements. Let us now return to the latter for an instant, 

 taking up the liver cells. One meets in them, from time to 

 time, with brownish molecules and drops of fat. Both ap- 

 pear subsequently in the bile ; the former is the " biliary 

 coloring matter " (to repeat a crude expression of former 

 days), the latter becomes " cholesterine." Therefore, even 

 here, the gland cell once enclosed in its body the secretory 

 substance which subsequently becomes free. Here the com- 

 ing and going of the latter through the permanent cell body 

 is not to be doubted. 



A still further confirmation of the persistence of many 

 gland cells has been more recently obtained. Extraordinarily 

 fine permanent canaliculi, "the gland capillaries" (first found 



in the liver), occur between the gland cells 

 as the terminal offshoots of the excretory 

 ducts. Our Fig. 125 represents such from 

 the pancreas. We shall, later, refer to 

 the matter more in detail. 



With the membrana propria and the 

 secretory cells we are, therefore, finished. 

 Let us now refer to the capillary reticu- 

 lum, the art and manner in which the in- 

 dispensable blood current reaches the 

 surface of the secreting organ. 



We repeat what we said at page 96. 

 The form of the tissue elements deter- 

 mines the arrangement of the capillaries. 



With thin and long glandular tubes, such as stand close to 



tn. e 



Fig. 125. — From the pan- 

 creas of the rabbit ; a, larger 

 excretory duct ; £, finer one 

 of an acinus ; c, finest secre- 

 tory canal. 



