CATALYZERS OF GROWTH 



505 



remarkably increased. Sweet, Corson-White and Saxon had a strain 

 of carcinoma which had never been known in their experience to yield 

 metastases in rats. They administered cholesterol by mouth to a large 

 number of rats inoculated with this tumor and obtained metastases 

 in over ninety per cent, of the animals. It has also been shown by 

 Browder that cholesterol has a remarkable influence upon the rate of 

 multiplication of the infusorian Paramecium, increasing the number 

 of generations produced in a given period by several hundred per cent. 

 If cholesterol be administered to young mice in dosages of 40 mgm. 

 per day, however, a result is obtained which is at first sight rather 

 surprising, for the growth of the animals, instead of being accelerated, 

 is very markedly retarded during the early weeks of the third growth- 

 cycle (fifth to fifteenth week) and subsequently undergoes a secondary 

 acceleration which, however, never makes up for the ground lost during 



d 



70 80 90 100 110 120 130 140 160 



WEEKS 



5 10 15 20 25 30 40 50 



FIG. 40. Influence of cholesterol upon the growth of male white mice. Dosage, 

 40 mgms. per day. The vertical cross-mark indicates average duration of life. 



the period of initial retardation (Fig. 40). Now when cholesterol is 

 administered in unusual amounts to animals the excretory mechanisms 

 prove insufficient and large deposits are formed in a variety of organs, 

 particularly the liver, spleen and suprarenal capsules, and it might be 

 imagined that this or some other deleterious effect of cholesterol, 

 superadded to its effect upon growth is responsible for the retardation 

 of the growth in weight of animals to which its administration leads. 

 This, however, is not the case, for this effect of cholesterol is merely 

 a particular instance of the general action of growth-catalyzers upon 

 the adolescent growth of animals. 



It will be recollected that the administration of the tissue of the 

 Anterior Lobe of the Pituitary Body to growing animals produces a like 

 unexpected result, namely a retardation of the early adolescent growth 

 followed by a secondary acceleration. Now hypophyseal tissue, when 



