508 



SCIENCE 



[N. S. Vol. XLIII. No. 1110 



the coagulation point (Fig. 1, B). Owing to 

 this peculiar property of coagulation, which 

 is, physically, an increase in the state of aggre- 

 gation, whatever may be the nature of the 

 chemical processes involved, we have here 

 opposite effects produced by a slight and con- 

 siderable increase in temperature, respectively; 

 the effect of heat may be either liquefactive^'' 

 or coagulative. We should expect, a priori, 

 that by adding a powerful liquefying agent to 

 an hydrophilous colloid, the coagulative effect 

 of heat might be overcome wholly or in part, 

 since this would introduce a dispersion factor 

 into the equilibrium. This actually occurs as 

 Pauli^^ and Pauli and Handovsky have 

 shown. Pauli found that upon adding neutral 

 thioeyanates, which are powerful liquefying 

 agents, to egg-albumin, it could not be coagu- 

 lated even at the boiling point of the mixture. 

 Four years ago I observed that the liquefy- 

 ing effect of atropine or atropine sulphate 

 upon the melanophores of Fundulus could be 

 distinctly reduced by sufficiently elevating the 

 temperature of the solution. Eecently^^ I 

 have found that for temperatures up to ap- 

 proximately 36° C, atropine shows a normal 

 positive temperature coefficient, i. e., the lique- 

 fying effect increases with a rise in tempera- 

 ture. If, however, we expose contracted melan- 

 ophores to identical solutions of atropine at 

 22° C. and at 37° C. for a period of five min- 

 utes, the cells from the warm solution show 

 distinctly less liquefaction than those at room 

 temperature. That the cell colloids are not 

 coagulated by the higher temperature is shown 

 by the activity of the cell upon being returned 

 to ISTaCl or KCl solutions. Thus in this case, 

 for a few degrees, between 36° C. and the ele- 

 vated coagulation point of the cell protoplasm 

 (< 43° C.) the temperature coefficient of 

 liquefaction for atropine becomes negative 

 (Fig. 1, A). From the foregoing considera- 

 tions we shoidd expect an elevation in tem- 

 perature to increase the solubility of the dis- 

 perse phases at the surface of the melano- 



i4Tn11ie, E. S., '15, Biol. Bulletin, 28, 260. 

 "Pauli, W., '99, Pflugers Arch., 78, 35; Pauli 

 u. Handovsky, '08, Hofmeisters Beitr., 11, 415. 

 16 Unpublislied experiments. 



phore.^^ We have, in addition, the liquefying 

 effect of the atropine. Hence we have here 

 the combined liquefying effect of atropine and 

 elevated temperature, i. e., two forces tend- 

 ing to drive the disperse phases of the ceU sur- 

 face into solution and to increase their de- 

 gree of dispersion. Beyond 36° C, however, 

 further increase in temperature tends to initi- 

 ate the first steps in the process of heat coagu- 

 lation involving a decrease in the state of 

 aggregation of the surface colloids. The in- 

 hibition of the atropine effect above 36° 0. is, 

 therefore, to be interpreted as due to an ele- 

 vation in the viscosity of the surface colloids 

 which retards the diffusion of the alkaloid into 

 the cell. Bearing in mind these antithetical 

 physical effects of low and high temperatures, 

 it appears that the experimental data both in 

 the case of colloidal solutions of egg-white and 

 in that of living cells (melanophores) comply 

 well with the theory.^^ A liquefying agent in 

 proper concentration may prevent heat coagu- 

 lation and, reciprocally, a sufficient elevation 

 in temperature may protect the system against 

 liquefaction. 



These physical-chemical relations may offer 

 an explanation of the extraordinary habit of 

 certain blue-green alga which normally thrive 

 at a temperature of 68° C.^^ The water in 

 which these algae live contains numerous salts 

 in solution and we suspect at once that among 

 these salts there is a powerful liquefying agent 

 which prevents coagulation by the abnormally 

 high temperature, as in Pauli'a experiments 

 upon egg-white. We should expect that a re- 

 duction in temperature would prove fatal to 

 such algse since, under these altered circum- 



1' It is impossible to carry out an experiment 

 upon the melanophores of Fundulus which is di- 

 rectly comparable to Pauli 's experiments on the 

 elevated coagulation point of egg-white. KSCN 

 produces a marked liquefaction upon the melano- 

 phores, but only after a relatively long exposure 

 (< 30 minutes). Atropine, on the other hand, 

 brings about an irreversible disintegration at room 

 temperature in concentrations of ea. 0.004 M in 

 0.1 M NaCl in about five minutes. 



18 See also Lepeschkin, W. W., '11, Ber. d. 

 deutseh. hot. Gesellsoh., 29, 247; '13, ibid., 30, 703. 



i» Setchell, W. A.j '03, Science, 17, 943. 



