September 29, 1911] 



SCIENCE 



415 



kidney tissue. This organism had been in- 

 jected into the circulation of a rabbit and at 

 various periods after the injection pieces of 

 the kidney were transferred into the culture 

 media. In these experiments we found not 

 only that both kidney tissue, stroma and 

 parenchyma, and organism may grow side by 

 side in tiie culture media, but that under cer- 

 tain conditions the growth of the kidney cells 

 may be quantitatively increased. 



It will be of interest to extend these studies 

 to other well-defined microorganisms and to 

 test the effect of their metabolic products and 

 direct action on tissue growth. 



3. The stereotropie sensitiveness of connect- 

 ive tissue cells can very well be observed in the 

 process of atresia of the ovarian follicle. At 

 a period when the degeneration of the granu- 

 losa has set in, connective tissue cells begin to 

 grow from the surrounding theca into the fol- 

 licular cavity and to fill it more or less com- 

 pletely. Here we, can notice that usually the 

 connective tissue cells do not grow directly 

 into the cavity but move in contact with the 

 wall of the follicle, thus forming a peripheral 

 layer of connective tissue which gradually en- 

 larges as more cells are added. 



In certain cases, however, we may observe 

 that connective tissue cells grow directly into 

 the cavity. In these cases it is probable that 

 the viscosity of the follicular fluid is relatively 

 great and that a viscous fluid may permit a 

 direct ingrowth of some tissue cells. 



Leo Loeb 



Department or Pathology, 



Barnard Skin and Cancer Hospital, 

 St. Louis 



' OS" AN interpolation formula used in cal- 

 culating TEMPERATURE COEFFICIENTS FOE 

 VELOCITY OF VITAL ACTIVITIES, TOGETHER 

 WITH A NOTE ON THE VELOCITY OF 

 NERVE CONDUCTION IN MAN 



Inquiries, both written and verbal, have 

 come to me asking for information concerning 

 a formula which has been employed in some 

 of my physiological papers on temperature 

 coefiicients. 



In this communication I wish to answer 



these inquiries (1) by referring to the ante- 

 cedents and mathematical significance of the 

 formula as briefly as I may, and (2) by giving 

 one or two examples of its application. 



In the first place it must be stated that the 

 formula in question, so far as my work is con- 

 cerned, is entirely an empirical one. Wherever 

 a series of quantities varies with some ex- 

 ponential factor the formula has been found 

 to be fairly satisfactory for extra- and inter- 

 polation. Its origin, as far as I (who am not 

 a mathematician) know, is probably " lost in 

 antiquity." Professor Max Bodenstein, of 

 Hanover, has told me, however, that he 

 thought Berthelot first used it in chemistry. 

 Just lately I find that Bodenstein' himself 

 made use of the formula in 1899 for the deter- 

 mination of the temperature coefiicient of 

 chemical reaction velocities. 



On the other hand, the formula of van't 

 Hoff" and Arrhenius,' among others, were de- 

 veloped from thermodynamic considerations 

 and therefore have important theoretical 

 foundations. 



However, the formula I use. 



A^\ ^1—^0 _ 



(I) 



Qu 



(1) 



is practically the same, I find, as one of van't 

 Hoff's,' namely, 



log„ J; = o-|- 6«. (2) 



For if the values of Tc in (2) for two different 

 temperatures are known, then this equation 

 may be derived: 



Equation (1) is probably more convenient 

 for the calculation of quotients for intervals 

 of 10 degrees (temperature coefiicients), but it 

 is also more cumbersome for the calculation 



^ Bodenstein, M., Zeitschrift fiir physikaliscke 

 Cliemie, 1899, Bd. 29, S. 332. 



- Van 't Hoff, ' ' Etudes de dynamique ehimique, ' ' 

 1884, p. 115. 



= Arrhenius, Zeitschrift fiir physikaliscke Chemie, 

 1899, Bd. 4, S. 226; " Immunoehemie, " Leipzig, 

 1907. 



■■ Van 't Hoff, Vorlesungen iiber theoretische und 

 physikalische Chemie, 1898, I., S. 224. 



