380 COLLOIDS IN BIOLOGY AND MEDICINE 



stead of : - (concentration of the salt in the dispersed phase) he 



placed - , in which t = length of life; - is accordingly the toxicity. 



1 

 The equation becomes = k. Wo. OSTWALD experimented with the 



P 



sand flea mentioned (gammarus pulex) and with another small crus- 

 tacean (daphnia magna). He placed a given number of them, e.g., 

 twenty-five, in a definite quantity of water (100 cc.) of different salt 

 concentration and every two minutes he observed how many had 

 meanwhile died. It was evident that the zero point of the adsorp- 

 tion curve must be placed to coincide with the normal salt con- 

 tent of the organism, and that either a dilution or a concentration of 

 the surrounding water is toxic. This must be expressed in the ad- 

 sorption equation. Accordingly, the toxicity formula for neutral 



1 



salts, when their concentration is increased, is = k' } in 



(-)- 



this case n is the quantity of salt normally adsorbed in the tissues. 



For the toxicity of subnormal salt solutions, the adsorption for- 

 mula becomes - C = k. Wo. OSTWALD * 4 calls the latter the 

 t p 



"formula of leaching." Observed and calculated results agree quite 

 well. 



A peculiar place is occupied by potassium iodid and iodin com- 

 pounds. With all of them, the "iodin action" is the most im- 

 portant; we may even assume that the iodin of nonelectrolytes 

 finally becomes an iodin ion. The emaciation caused by its pro- 

 longed internal use and the atrophy of certain glands are the most 

 characteristic iodin effects upon higher animals. Prolonged use of 

 iodin preparations, according to H. MEYER and R. GOTTLIEB,* 

 among others, causes an excessive secretion from mucous mem- 

 branes, which is an inflammatory reaction. Even though metab- 

 olism experiments have not revealed any constant variations from 

 the normal, it may be recalled that according to the experiments of 

 H. BECHHOLD and J. ZIEGLER (see p. 54) potassium iodid facilitates 

 the diffusion of a third substance through a jelly. All the phenomena 

 mentioned above indicate a facilitation of metabolism. As was to 

 be expected potassium iodid (according to E. ROMBERG) lowers the 

 viscosity of the blood, and according to O. MULLER and R. IN AD A* 



