764 EXPERIMENT STATION RECORD, 



28 per cent In the other, and since these variations have no parallel in those of 

 any other metabolic products determined, the possibility of absorption through 

 the skin seems evident" 



A new respiratory chamber, A. C. Kolls and A. S. Loevenhaet (Proc. Amer. 

 8oc: Biol. Chem., 3 (1913), No. 1, pp. 32, 33). — A summary of a paper presented 

 at the eighth annual meeting of the American Society of Biological Chemists at 

 Philadelphia, Pa., in December, 1913. A respiratory chamber designed for the 

 purpose of determining the effect of reducing the oxygen of the respired air on 

 the erythrocyte and hemoglobin content of the blood is described. 



A self-recording calorimeter for large animals, A. V. and A. M. Hill {Jour. 

 Physiol, 48 (1914), No. 1, pp. XIII, XIV). — The authors describe a calorimeter 

 constructed accorduag to the same principle employed hi a smaller one previ- 

 ously noted (E. S. R., 29, p. 569). The apparatus consists essentially of two 

 horizontal co-axial iron cylinders separated by an insulating medium of saw- 

 dust and kapok wool and is of a size suitable for experiments with a sheep or 

 dog. 



A simple and convenient form of bicycle ergometer, C. J. Martin (Jour. 

 Physiol, 48 (1914), No. 1, pp. XV, XVI, fig. i).— An ergometer of the brake type 

 is described in which the work done in foot-pounds is calculated from the frlc- 

 tlonal pull, the circumference of the wheel, and the number of its revolutions. 



For the rear wheel of the bicycle Is substituted a cast-iron one weighing 22 

 kg., the friction being supplied by means of a stout linen band passing around 

 the circumference of the wheel, the ends of the band being so attached to 

 spring balances that the friction may be easily adjusted. The advantages 

 claimed for this piece of apparatus are that the subject of the experiment may 

 make all the necessary observations ; that " it has an error of less than 1 per 

 cent " ; that " the frictional pull is steady and Is nearly independent of the 

 velocity, so that It is not necessary to pedal always at a constant rate"; that 

 " the instrument can be adjusted for any rate of work at any pedal revolution 

 desired " ; and that " the friction band is quite thin and so does not get hot 

 and vary the pull during the experiment." 



ANIMAL PRODUCTION. 



Bibliography of physiology (Bibliofjraphia Physiol, 3. ser., 8 (1912), Nos. 1, 

 pp. 112; 2-3, pp. 113-384; 4, pp. 385-500; Index, pp. 501-613).— A bibliography 

 of American and foreign works and articles on physiology and biochemistry 

 received during 1912. 



On the correlation between the number of mammae of the dam and size of 

 litter in mammals, R. Pkarl (Proc. Soc. Expt. Biol and Med., 11 (1913). No. I. 

 pp. 27-32). — This includes two papers. 



I. Interracial correlation (pp. 27-30). — Biometrical methods are applied to an 

 extensive series of statistics regarding size of litter and number of mammae for 

 many different species of wild and domestic mammals as collected by C. F. Bel- 

 llngeri in 1849. It Is found that " interracially the mean size of litter Is ap- 

 proximately two individuals below the mean number of mammae possessed by 

 the mother. This may be taken as a rough measure of the evolutionary ' factor 

 of safety ' in regard to these characters. There is relatively . . . somewhat 

 more variation exhibited In size of litter than in number of mammae. The cor- 

 relation between these two characters, as measured by the coefficient r. Is sur- 

 prisingly low. This result certainly can not be said to furnish particularly 

 strong evidence that natural selection has had anything to do with fixing the 

 relationship between number of mammse and size of litter." 



