418 RAYMOND PEARL AND M. R. CURTIS 



cavity but there is no evidence that any secretion had been 

 formed by the duct. Closing the mouth of the duct does not 

 prevent the duct from passing through the cychc changes which 

 are coordinated with the cychc changes in the ovary. The duct 

 glands, however, do not ordinarily discharge their secretion 

 except under the stimulation of the presence of the yolk. This 

 is in accord with the result of Pearl and Surface ('09 a) on the 

 shell gland. 



Cases 9 to 14 show the effect of closing the duct at other 

 levels. The duct was closed by a ligature in cases 9 and 10; 

 by an operation which resulted in the permanent shrinking 

 of a small portion of the tube in cases 11 and 12; and by the 

 section of the duct between two ligatures in cases 13 and 14. 

 In all these cases the oviduct was in full functional condition 

 at autopsy. In every case the duct on both sides of the liga- 

 ture or cut had enlarged to the size of an oviduct in a laying 

 bird. Yolks had entered these ducts and had stimulated the 

 secretion of the duct as far as the point where the passage was 

 closed. In no case was there any secretion posterior to the 

 ligature. That is, the whole duct enlarged but it was able to 

 function only under the stimulation of the advancing egg. 



There is possibly a difference in the final response of the 

 duct according to the level at which the passage is stopped. 

 Where the duct was closed through the shell gland (cases 9 

 and 14), membrane covered or soft shelled eggs were formed and 

 passed back up the duct into the body cavity. In cases 11 and 

 12 the ducts were closed at the isthmus and in each case the 

 duct above this point was filled with masses of secretion which 

 surrounded yolks but they did not pass back into the body 

 cavity. In case 12 there were yolk masses in the body cavity 

 surrounded by peritoneum but these did not appear to contain 

 albumen. It is possible that an egg cannot stimulate sufficient 

 antiperistalsis to cause its extrusion from the duct until it has 

 become somewhat firm by the formation of the egg membrane. 

 The number of cases, however, are too few, and the possibility 

 of the operation of other causes too great, to place much weight 

 on this interpretation. 



