NORMAL AND PATHOLOGICAL GROWTH 165 



according to the degree of injury, or intensity of function of 

 the other. It has been argued that the influence is reciprocal. 



Furthermore, each of these glands influences the gonads. 

 Smith and Engle by repeated transplants of anterior pituitary 

 gland tissue into the muscles of young mice induced not only 

 precocious development of the oestrus but a pronounced over- 

 growth of the gonads. The mass of the ovaries of mice were as 

 much as nineteen times and rats ten times those of untreated 

 litter mates. Furthermore, "superovulation, or the liberation of 

 an unusual number of ova invariably occurs." They found 

 "forty-eight apparently normal ova in one tube in a twenty-day- 

 old mouse, and in a twenty-six-day old rat." Young rats mature 

 at about forty to sixty or more days of age. The transplanted 

 tissue contains a hormone which stimulates the development of 

 the follicles, bringing more embryonic follicles and ova to full 

 maturity. In the absence of the anterior pituitary hormone the 

 gonads degenerate. When it is supplied again they grow and 

 normal functions are reestablished. 



Dwarfism on the other hand and the persistence of infanti- 

 lism beyond the usual age of puberty in the human are ex- 

 amples of anterior pituitary inactivity, namely, lack of pituitary 

 hormone formation or hypo-pituitaryism. Both pituitary lobes 

 are often involved. A failure of the normal growth of the 

 pituitary and of the normal amount of secretion of the pituitary 

 occurring in early childhood, is accompanied by failure of the 

 usual rapid growth in height and weight characteristic of the 

 age of puberty in both boys and girls. The skeleton does not 

 grow to its full capacity, the muscles do not develop to the usual 

 extent, the skin remains childlike in texture, and the facial 

 features, the beard, and other external changes characteristic of 

 adolescence are absent, and the external genital organs remain 

 childlike and infantile. There is often a peculiarly excessive 

 deposit of fat so that these cases are overweight for their height. 

 Hypopituitaryism may occur after adulthood is reached, due to 

 causes unknown. The picture, however, is clear cut and char- 

 acteristic. 



