410 RAYMOND PEARL AND M. R. CURTIS 



Bartelmez ('12) has shown that in the pigeon continued yolk 

 formation increases the pressure within the follicle so that 

 ''the egg bulges out when the rupture begins" and "the egg 

 is over a millimeter in diameter greater after ovulation than 

 the whole follicle was before." He and other workers recognize 

 in this increase in internal pressure an important factor in the 

 rupture of the follicle. 



That the pressure of the infundibulum is not necessary for 

 the rupture of the follicle is proven by the experiments of Sell- 

 heim ('07), which show that after the oviduct is removed ovula- 

 tion takes place into the body cavity. This result is confirmed 

 by the present investigation which shows that ovulation into 

 the body cavity occurs when the funnel mouth is closed by sew- 

 ing or ligating the ostium (cases 1, 4, 7 and 8), or by removal 

 of the duct (cases 15, 16, 18 and 19). In cases 4, 8, 15 and 

 17 the birds were killed during a normal period of egg produc- 

 tion and (with the exception of case 17) showed evidence of 

 recent ovulation into the body cavity. In these birds none 

 of the yolks remaining in the ovary were apparently larger than 

 yolks found in the ovaries of normal laying birds of the same 

 breed. Quantitative data are not as yet available on this 

 point, but the observations indicate that absence of pressure 

 exerted by the funnel does not perceptibly delay ovulation. 

 This suggests not only that internal pressure is a sufficient 

 cause for rupture of the follicle, but also that it may be the 

 most important factor in causing such rupture in the case of 

 normal ovulation into the oviduct. 



THE EFFECT OF PREVENTION OF EGG-LAYING ON BODY 



METABOLISM 



It has already been shown that if the oviduct is removed 

 or if the mouth of the duct is permanently closed the ovary 

 passes through normal periods of egg production and the yolks 

 are ovulated into the body cavity. Cases 9, 10, 12, 13 and 

 14 show that when it is possible for a yolk to enter but not to 

 leave the duct, the duct may be filled with egg masses and ovu- 



