THE PITUITARY BODY 



extensive experiments are those with rats Hving in parabiosis; 

 in such animals the hormone(s) apparently are carried in the 

 blood. In rabbits, Brambell and Parkes (1932) found that the 

 anterior pituitary hormone, liberated as a result of copula- 

 tion, could still cause ovulation after the removal of 30 per 

 cent of the blood; if 40 per cent was removed, ovulation did 

 not occur unless the mass of ovarian tissue (follicles) was first 

 reduced. Later experiments (McPhail, Parkes, and White, 

 1933) showed that 50 and even 60 per cent of the blood could 

 be removed without preventing ovulation. In most of these 

 later experiments the ovaries were left intact. 



If anterior pituitary extract is administered by way of the 

 gastrointestinal tract, gonadotropic effects are not observed 

 unless the dose is 15-30 (rabbit; Lepine, 1931) to 100 (rat; 

 Janssen and Loeser, 1931) times as great as the parenteral 

 dose. Goodman and Wislocki (1933) administered anterior- 

 lobe extract intravenously to pregnant rabbits and cats; sub- 

 sequently, they could find no gonadotropic hormone (ovula- 

 tion test in the rabbit) in either the amniotic or the allantoic 

 fluids. 



If gonadotropic extract obtained from the anterior lobe of 

 other (different) animals is repeatedly injected into immature 

 rats, rabbits, etc., the gonadotropic effects tend to recede and 

 may finally disappear. Collip and his colleagues have sug- 

 gested that the hormone effects are antagonized by antibodies 

 ("antihormones") produced by the animal receiving the in- 

 jections. In favor of this view there is considerable evidence 

 which cannot be evaluated until pure gonadotropic hormone 

 (or hormones) is available for study. ^^ That "antihormones" 

 are of physiological significance is doubtful. It is true that 

 the effects of homoplastic implants may be slight if daily ad- 

 ministration is continued for 2-3 months; however, the ad- 

 ministration of gonadotropic hormone in this way, suitable as 



5' See Bachman, Collip, and Selye (1934); and Selye, Collip, and Thomson 

 (1934). There is further discussion in chap. v. 



[166] 



