350 



SCIENCE 



[N. S. Vol. LI. No. 1318 



This paper presents the development of a 

 general method of ascertaining the relation 

 between a dependent variable and each of a 

 number of mutually correlated ones without 

 ieing compelled to employ an assumed or pre- 

 determined mathematical function. This is 

 accomplished by applying to the observed 

 values of the dependent variable successive 

 corrections based upon each value of all the 

 independent variables. In this way is ob- 

 tained a series of averages of the dependent 

 variable corresponding to a series of averages 

 of each one of the independent variables in 

 turn and corrected to a constant value of each 

 of the remaining ones. The method is con- 

 cretely illustrated by an application to a bio- 

 climatic problem; that of predicting the yield 

 of South Dakota wheat from temperature and 

 precipitation. 



A limited number of reprints are available 

 for distribution. Requests for them should be 

 mailed to the Scripps Institution, La Jolla, 

 California. 



G-EO. F. McEwEN 

 Ellis L. Michael 



THE AMERICAN CHEMICAL SOCIETY 

 VII 



Calorvmetric determinations of the energy in 

 yoVk-protein and yolk-fat of doves and pigeons: 

 OsCAK EiDDLBS. Individual entire egg-yolks were 

 separated into (boiling) alcohol-ether soluble and 

 insoluble fractions. These moisture-free portions 

 considered as yolk-protein and yolk-fat were 

 burned in a Eiche bomb calorimeter. Determina- 

 tions were separately made upon yolks from vari- 

 ous pure species and hybrids. The energy per 

 gram of the yolk-protein of pure species averages 

 5,497 (small) calories; for hybrids praatically the 

 same (5,457). The energy per gram of yolk-fat 

 of pure species averages 9,020 calories; for hy- 

 brids probably it is less (8,897). The range of 

 variability for yolks from individual hybrids is 

 plainly greater than for yolks from pure species. 



Some properties of the placental hormone: Paul 

 M. GiEST. This substance, injected subcutaneously 

 into the female animals, causes growth of the 

 mammary glands and uterus. It was extracted by 

 treating ground placentas with alcohol. In water, 

 some, but not all, of the substance dissolves. It is 

 dissolved by benzene, chloroform, carbon tetra- 



chloride, absolute alcohol, ether and ethyl ace- 

 tate, but not hj petroleum ether. If the extract is 

 shaken with a mixture of water and benzene, the 

 benzene solution alone is physiologically active. 

 Alcoholic solutions and aqueous emulsions lose their 

 activity on standing. The activity appears to be 

 destroyed by continued heating. 



The preparation of fatty acid esters of choles- 

 terol: G. D. Beal and J. B. Brown. (By title.) 

 Comparative analysis of fiirin in the presence of 

 various aldehydes: George E. Holm and Boss 

 Aiken Gortner. The comparative action of vari- 

 ous amounts of paraldehyde, benzaldehyde, butyl 

 and isobutyl aldehydes to that of formaldehyde 

 when present in the acid hydrolysis of fibrin and 

 gelatin was studied. In all cases the acid insoluble 

 humin nitrogen increase is greater than with 

 (CHjO), and a maximum is reached and main- 

 tained even in the presence of large excesses of 

 these aldehydes. The ammonia nitrogen, soluble 

 humin nitrogen and total amino nitrogen of the 

 filtrates from the "humin" do not alter signifi- 

 cantly. Using triosymethylene, the increase in 

 insoluble humin nitrogen is due to the presence of 

 the indole nucleus, while with the other aldehydes 

 tyrosin also enters into this reaction. 



The preparation of cholesterol in quantity: Paul 

 M. GiEST. One hundred pounds of cattle spinal 

 cords were ground, dehydrated with alcohol and 

 extracted fourteen times with ether. The ether 

 was evaporated from the extract, and the residue 

 saponified by boiling with alcoholic sodium hydrox- 

 ide. After evaporating the alcohol, the residue 

 was taken up in water and extracted with ether. 

 The ether was evaporated from the extract, and 

 the cholesterol crystallized from alcohol. The first 

 crop was cream-colored and melted at 147.1° cor- 

 rected. The second crop was brown, and melted at 

 146.4°. The total yield is about two pounds. The 

 color can be removed by reerystallization from 

 alcohol. 



The influence of aspartic acid and asparagin 

 upon the eneymic hydrolysis of starch : H. C. Sher- 

 man AND Tlorence Walker. (By title.) 



An improved technic for measuring lipase activ- 

 ity in animal or plaint extracts or tissues : Lerot S. 

 Palmer (By title.) The material to be tested is 

 added in the form of an extract or finely minced 

 paste to at least 75 c.c. of artificial "mUk," pre- 

 pared by grinding a suitable oil into hydrated 

 acacia and diluting the emulsion with water. 

 HCHO 1: 1,500 is added to the "milk" as preserv- 

 tive. The initial acidity is determined by with- 



