PHYSIOLOGY OF THE OVIDUCT 413 



very many which were just distinguishable. The ovary also 

 contained a normal series of maturing yolks. Four of these 

 were above 1 cm. in diameter. The largest was apparently 

 mature. 



These two birds then had normal ovaries and at the time 

 of death were maturing and o\iilating yolks at a rate com- 

 parable to that shown by birds at the height of a normal period 

 of egg production. They also possessed oviducts which were 

 apparently able to secrete the normal enclosing envelopes. 

 The fact that the yolks did not enter the duct and become 

 the yolks of normal eggs was probably due^ in the first case, 

 to the fact that the funnel mouth was too small to admit a 

 full sized yolk, and in the second to a lowered state of tonus 

 in the muscles of the oviduct and oviduct ligaments. They 

 represent a type of non-production previously discussed by 

 one of the authors (Pearl '12) where sterility is due to 'somatic' 

 (physiological) rather than 'gametic' causes. From the point 

 of view of the present investigation they show that a bird may 

 ovulate into the body cavity and resorb the yolks from the 

 general peritoneal surface at an astonishingly rapid rate without 

 causing any apparent disturbance of normal metabolism. 



In the second type of absorption in the body cavity the yolks 

 or eggs are enclosed in separate sheets of peritoneum by which 

 they are attached to the adjacent peritoneal surface. This 

 type of absorption has been several times observed in routine 

 autopsy work as well as in cases 4, 10, 12, 13, 18 and 19. Case 

 9 shows all the steps in the process. 



This bird's oviduct had been ligated at the level of the caudal 

 end of the shell gland before it has enlarged for its first period 

 of egg production. The sex organs developed normally. The 

 duct received the yolks and formed normal eggs which were 

 discharged back through the funnel into the body cavity. At 

 the time of autopsy the body cavity contained five normal and 

 two yolkless eggs, and there were also two normal soft shelled 

 eggs in the oviduct just above the ligature. The condition 

 and position of the eggs in the body cavity were as follows: 

 (1) A collapsed shell, slightly calcareous, containing a small 



