ggg EXPERIMENT STATION RECORD. [Vol.35 



therefore comparable with that produced by the administration of much smaller 

 doses of tethelin. The influence of cholesterol upon the variability of the ani- 

 mals to which it is fed is, however, directly opposite to the effect exerted by 

 tethelin, for while tethelin reduces the variability of the animals to which it is 

 fed, cholesterol increases their variability. This increase in variability is 

 mainly attributable to the very unequal acceleration, in different individuals, of 

 the latter portion of the third growth cycle. 



" Cholesterol-fed animals do not noticeably differ in build from normal ani- 

 mals. Their coats are smoother and more glossy in appearance than those of 

 normal animals of the same age. Between the fifth and tenth weeks the testicles 

 of cholesterol-fed males become very prominent. This disproportion between the 

 size of the testicles and that of the animals bearing them rapidly disappears 

 subsequent to the tenth week. It is probably due to absence of retardation of 

 the growth of the testicles during the first five weeks of feeding, so that the 

 retardation of the body growth of the animals leads to disproportionate size of 

 the testicles. The subsequent acceleration of the body growth restores the 

 normal proportion. 



" No deleterious effects attributable to the feeding of cholesterol were ob- 

 served. Three animals which were examined after 50, 463, and 511 days of 

 feeding, respectively, showed no evidence of lesions in the wall of the aorta such 

 as are observed in rabbits after feeding relatively smaller doses for compara- 

 tively brief periods of time." 



VI. The influence of lecithin upon the growth of the white mouse (pp. 

 647-661). — In these studies it was found that "the administration by mouth of 

 80 mg. per day per animal of egg lecithin, beginning at four weeks after birth 

 (conclusion of the second growth cycle), leads to no deformation of the curve of 

 growth, the only demonstrable effects of the administration consisting in a very 

 slight uniform retardation of growth and a low degree of resistance to infection, 

 both effects being not improbably attributable to the injurious action of excess of 

 cholin absorbed from the alimentary tract. 



" The administration by mouth of 4 mg. per day of lecithin derived from 

 the anterior lobe of the pituitary body produces similar effects. Having regard 

 to the comparatively small dose administered it is possible that these effects 

 may in part have been due to admixture of other and more potent substances 

 with lecithin derived from this source, or at all events to a peculiarity of 

 lecithin derived from the anterior lobe of the pituitary body. 



"The lack of effect of lecithin administered by mouth in comparison with 

 its effects when administered subcutaneously or to lower organisms is probably 

 attributable to the fact that lecithin is completely split during digestion and 

 is not absorbed to any appreciable extent as such." 



VII. The influence of the administration of egg lecithin and of cholesterol to 

 the mother, upon the groivth of suckling mice (pp. 663-667). — The authors found 

 in these trials that " the administration of 100 mg. of egg lecithin per day by 

 mouth to the mother slightly retards the growth of suckling mice. The adminis- 

 tration of 100 mg. of cholesterol per day by mouth to the mother causes a very 

 marked retardation of tbe growth of suckling mice between the ninth and 

 twenty-first days after birth." 



It is not decided " whether these actions represent the direct effect of lecithin 

 and cholesterol upon the growth of sucklings or only an indirect effect due to 

 interference with the supply of milk." 



The mechanism of crossing-over, I, II, III, IV, H. J. MtJLLER {Amer. Nat., 

 50 {1916), Nos. 592, pp. 193-221, figs. 5; 593, pp. 284-305, figs. 4; 594, PP- 350- 

 366; 595, pp. 421-434, figs. 4)' — The author summarizes the results of his studies 

 as follows : 



