270 EXPERIMENT STATION RECORD. [Vol.41 



the right side \v(>re soverod. Tliis operation prevented voluntary movement of 

 the riplit front log but did not interfere with the bhjod supply. Contraction of 

 the muscles controlling the upper arm served to hold the leg close to the body 

 in a fixed position. The leg thus bore no weight and was subject only to slight 

 muscular pull. Growth of the bone in the living animal was studied by means 

 of radiographs. The subject was killed at the age of 23 weeks and a detailed 

 comparison made of the bones of the two front limbs. 



The long bones of the unused leg attained nearly the same length as those 

 of the other side but the diameters were only about half as great, due to de- 

 crease both in the amount of bone tissue and in the size of the marrow cavity. 

 The weight required to crush the bones of the operated limb was 14,84.5 lbs. 

 per square inch of bone cross section, only 19 per cent less than that required 

 for the normal bones. The unused shoulder blade was very thin and in places 

 entirely membraneous. 



The author concludes that bone development is not entirely controlled by the 

 mechanical stresses to which it is subjected. 



Effects of inanition and refeeding upon the growth and structure of the 

 hypophysis in the albino rat, C. M. Jackson (Atiicr. Jour. Anttt., 21 il!>17), 

 No. 2, pp. 321-358, figs. 5). — The experiments reported here were undertaken 

 because of the intimate relations that seem to exist between the pituitary body 

 (hypophysis cerebri) and the general growth process. A total of 91 rats, 

 young and adult, were used. The diet consisted of graham bread soaked in 

 whole milk and was varied only as to amounts fed. After an experimental 

 feeding period, the rats were killed and the body length, body weight, and 

 weight of hypophysis determined. These data are tabulated for each individual. 

 The volumes of the different parts of the hypophysis were estimated from serial 

 sections. 



During restricted feeding the relative proportions of parts were altered but, 

 except after long periods of maintenance, there was a gradual return to normal 

 upon refeeding. Coll division in the hypophysis generally ceased during under- 

 feeding, but there was no evidence as far as this organ is concerned in favor 

 of the suggestion of Osborne, Mendel, et al. (E. S. R., 34, p. 862) that accel- 

 erated growth following periods of suppression is due to specific histological 

 changes in the ductless glands. 



Cytological studies of the reproductive cells of cattle {Idaho Stn. Rpt. 

 WIS, p. 3.'t). — On the basis of an examination of the testes of a bull by J. B. 

 Wodsedalek, it is stated that there are 37 chromosomes in the spermatogonia 

 and that the unpaired one passes undivided, to one pole at the first spermato- 

 cyte (reduction) division. 



Composition and nutritive value of feeding stuffs, T. B. Wood and E. T. 

 Halnan {Cambridge, Eng.: Univ. Press [1918], pp. 24, figs. 6). — This is a com- 

 pilation in tabular form of proximate analyses of materials used by Briti.sh 

 farmers as feeding stuffs and of the available data as to digestible nutrients in 

 each, together with a computation of the nutritive ratio, the maintenance and 

 production starch equivalents, and the food units per ton. A series of charts 

 gives curves showing the relation of food requirem(>iits to body weights in the 

 different classes of live stock. 



The composition and food value of bracken rhizomes, J, Hendrick {Scot. 

 Jour. Agr., 1 {li>18), No. Jf. pp. .'f23-.'i30). — rroximato analyses of nine samples 

 of fresh washed bracken rhizomes and one sample dried and ground to meal 

 are presented, together with notes on the amounts to be secured from bracken- 

 infested pastures, the cost of digging, and the preliminary results of the feeding 

 trials noted below. It is stated that, in some cases at least, unringed pigs 

 learn to root up the rhizomes and eat them. 



