On the Experimental Production of Congenital Goitre. 323 



highly toxic and goitrigenous agencies during intra-uterine life, and to 

 contrast the results with those observed in the offspring of primiparte which 

 had as far as possible been protected from these influences. 



Conditions of the Experiment. 



For this purpose female goats of the first year, imported from a non- 

 goitrous locality in the plains of India, were used ; they were divided into the 

 following classes for observation : — 



Class A included 12 in which small goitres had been artificially produced. 

 They were confined in a pen 10 yards square, and permitted to mix freely one 

 with another. Throughout the experiment and during the whole period of 

 gestation they were fed daily on cultures of bacteria from the faeces of 

 goitrous individuals. 



Class B included eight females, non-goitrous goats, which were isolated one 

 from another by tethering them some distance apart. Four of them were also 

 muzzled so as to exclude the possibility of infection by contaminated food, 

 the muzzles being removed only at stated intervals when the animals were 

 fed. The remaining four were not muzzled. No cultures were administered 

 to any of them. 



Class C included one young female goitrous goat, from which I had 

 removed half the enlarged thyroid. The animal lived an entirely normal life 

 throughout the period of the experiment. 



The animals in all three classes were impregnated by the same non-goitrous 

 male during the same season — e.g., sometime after March 1, 1914, when the 

 experiment proper commenced. Their conditions of life were in every other 

 respect identical. Those in Classes B and C acted as controls to those in 

 Class A. 



The only factors, then, to which differences of results could be attributed 

 were : — 



(1) Intimate contact, in the case of animals of Class A. 



(2) Muzzling, in the case of one half of those in Class B. 



(3) The presence of goitre in the mothers of Classes A and C, and 



(4) The administration of the cultures to those of Class A. 



VOL. LXXXIX. — B. 



