3919] ANIMAL PRODUCTION. 567 



history, but which nevertheless naturalists are little accustomed to employ. It 

 is not the biologist with an Inkling of mathematics, hut the skilled and learned 

 mathematician who must ultimately deal with BUCh prohleins as are merely 

 sketched and adumbrated here." 



The topics treated include rate of growth, the form and structure of cells, 

 the dynamics of tissue formation, the use of the logarithmic spiral to describe 

 the shape of horns and tusks, the shape of hlrds' eggs, the mechanical efficiency 

 of the skeleton and the application of the theory of the transformation of co- 

 ordinates to the comparison of related forms. The last-named device consists 

 of drawing an outline of the form selected as a type In rectangular coordinates, 

 and then finding what deformations in the coordinates are necessary in order 

 to produce the form that is compared. In a wide variety of cases a linear trans- 

 formation is all that is necessary, a very simple matter mathematically but 

 somewhat complicated in practice since only empirical methods are as yet 

 available* 



Effect of limited food supply on the growth of young beef animals, P. F. 

 Trowbridge, C. R. Moulton, and L. D. Haigh (Missouri fita. Research Hid. 28 

 (III IS), pp. 8-129, figs. 26). — The investigations described here are a part of 

 the elaborate " use of food " project of the Missouri Experiment Station. The 

 object as formulated in the outline prepared by H. J. Waters was " to determine 



(1) if an immature animal can use its stored fat to protect growth when 

 sparsely nourished, and to what extent the body fat may be relied upon to sup- 

 plement a limited ration to insure the continuation of the process of growth; 



(2) what changes occur in the composition of the body of immature animals 

 when held for a considerable time on a so-called maintenance ration, and also 

 what changes occur when such animals are kept on a ration above maintenance, 

 but not in sufficient quantity to supply the maximum growth of which the 

 animal is capable." The work has a bearing in the common practice among 

 tanners of bringing young cattle through the winter with almost no gain in 

 weight, the animals making a marked skeletal growth but becoming emaciated 

 and unthrifty. 



J. M. Eward was responsible for the selection, management, and measure- 

 ment of the animals, and the authors for the accuracy of the slaughtering data 

 and the analytical results. 



In October, 1907, a number of related steers dropped the preceding spring 

 were assembled and fed liberally, and from these a group of seven, as uniform 

 as possible, was selected for the actual experiment. Six were to be fed in a 

 designated manner, 3 for 6 months and 3 for 12, then slaughtered and a complete 

 chemical analysis of the carcass made. Tin- seventh was to be killed at the 

 beginning of the experiment, the chemical composition of its carcass serving 

 as the assumed initial percentage composition of the lot. Since the experiment 

 was to be primarily a study of the use of body fat, the thinnest steer was 

 selected as the check animal so that an initial difference between it and one of 

 the other animals would not be attrihuted to the after-treatment which the 

 latter received. The two fattest and most thrifty steers (Nos. 503 and 599) 

 were selected to be fed so as to gain a half pound a day. It was hoped that these 

 two would have a natural growth rate in excess of a half pound and so would 

 draw on their reserve fat to satisfy the persistent growth requirements of the 

 skeleton. The next fattest pair (Nos. 507 and 505) were to be fed so as to 

 maintain uniform body weight, and the remaining pair (Nos. 501 and 502) 

 so as to lose a half pound a day. Since the animals were all young it was 

 thought that those with less apparent growth capacity could better withstand 

 the rigors of undernourishment. 



