66 EXPERIMENT STATION RECORD. 



production of the animal body could be attributed to the work of the kidneys, 

 in the case of the rat, and 7.9 per cent in the case of the dog. 



A calorimeter for small animals, F. Tangl {Biochem. Ztschr., 53 (1913), 

 Ao. 1-2, pp. 21-35, figs. 3).— A description is given of a small calorimeter of the 

 open-circuit type which consists essentially of two small copper cylinders in- 

 serted in Dewar flasks, which, in turn, are inclosed in a copper box with cork 

 insulation. 



The difference in temperature between the two cylinders is measured by 

 means of thermoelectric junctions connected to a galvanometer. One of the 

 cylinders contains a rheostat and in the other is placed the animal whose heat 

 production is to be studied. During an experiment electricity is supplied to the 

 rheostat to generate a quantity of heat sufficient to compensate that given off by 

 the animal in the other cylinder, and thus the two cylinders are kept at the 

 same temperature. The amount of heat produced by the subject is determined 

 from the amount of current supplied to the rheostat. 



Provision is also made for the measurement of the carbon dioxid and water 

 vapor produced during the experiment, so that the instrument may serve both 

 as calorimeter and respiratory apparatus. 



Micro-calorimeter for the determination of the heat production of bac- 

 teria, K. VON KoRosY (Hoppe-Seyler's Ztschr. Physiol. Chem., 86 {1913), No. 5, 

 pp. 383-400, figs. 2). — ^A description is given of a micro-calorimeter which 

 utilizes the heat of vaporization of ether as a means of indicating the heat 

 production. The number of calories developed by the subject is measured 

 directly by the amount of ether distilled over during the experiment. 



ANIMAL PRODUCTION. 



The measurement of the intensity of inbreeding-, R. Pearl (Maine Sta. Bui. 

 215, pp. 123-138). — In this treatise is presented " a general method of measuring 

 the intensity or degree of the inbreeding practiced in any particular case." On 

 the basis that " the inbred individual possesses fewer different ancestors than 

 the maximum possible number," the author presents the following formula for 

 determining a coefficient of inbreeding: 



100 (pn+i-qn+i) 

 Vn+\ 



in which p^+i denotes the maximum possible number of different individuals 

 involved in the matings of the n+1 generation and g^+i the actual number of 

 different individuals involved in these matiugs. It is evident that the coefficient 

 of inbreeding Z is the percentage of the difference between the maximum pos- 

 sible number of ancestors and the actual number realized. In this method the 

 author starts with the individual in question and works backward, assuming 

 that all the different individuals are entirely unrelated until the contrary is 

 proved by the finding of a common ancestor. 



In the mating of brother with sister for a series of generations, it is shown 

 that " in the last 2 ancestral generations X is 50 per cent inbred; in the last 3 

 generations it is 75 per cent inbred ; and in the last 4 generations it is 87.5 pel 

 cent inbred." After the seventh generation there is relatively little change 

 made by further generations of this sort of breeding. It is shown that " while 

 increase in intensity of inbreeding is not so rapid in the first few ancestral 

 generations by parent X offspring type of breeding as with brother X sister 

 type, by the time the tenth ancestral generation is reached the values are, for 

 practical purposes, the same." 



