Jacques Loeb 533 
Some of the experiments have already been published.® Into 
a cylindrical funnel 2 gm. of finely powdered non-bleached? Cooper’s 
gelatin are put; the powder is held in the cylinder by a circular 
piece of filter paper. Three such funnels each with 2 gm. of 
gelatin are prepared. The one (I) is perfused six times in suc- 
cession with 25 cc. of distilled water; the second (II) is perfused 
twice with 25 ec. M/8 NaCl and then four times with 25 cc. of 
distilled water; the third (III) is perfused six times with 25 ce. 
M/8 NaCl. In I and III a moderate swelling occurs, which soon 
reaches its maximum. The gelatin in II, first treated with NaCl 
and subsequently with distilled water, swells several hundred 
per cent more than either the gelatin treated only with distilled 
water (I) or the gelatin (III) treated only with NaCl. 
The explanation of this experiment is as follows. Gelatin II 
forms under the influence of a comparatively high concentration 
of NaCl (4/8 or mM/4) a compound with NaCl which is capable 
of ionization. This ionization is lowered through the presence of 
the highly concentrated NaCl solution. When, however, this 
latter solution is washed away by successive perfusions of the 
gelatin with distilled water the gelatin-NaCl compound can dis- 
sociate into gelatin and an inorganic ion, the nature of which we 
shall discuss later. It has been shown by Pauli and by Procter! 
- that the swelling of protein under the influence of acid or base is 
due to the ionization of protein by the acid and the writer as- 
sumes that the increase in the amount in swelling of the mass of 
gelatin first treated with NaCl and then washed with distilled 
water is due to the fact that part of the gelatin is transformed into 
protein ions by the salt, and that this ionization and the swelling 
can only appear when the NaCl solution held in the capillary 
spaces of the powder is washed away. This statement is sup- 
ported by the following facts. 
1. A large number of funnels are prepared, each with 2 gm. 
of powdered gelatin and each is perfused twice with 25 cc. M/8 
NaCl. Subsequently each funnel is perfused three times with 
8 Loeb, J. Biol. Chem., 1917, xxxi, 343. 
® Bleached gelatin as well as bleached pig’s bladder does not give the 
same results, probably on account of an alteration in the constitution of 
the protein. 
10 Procter, H. R,, and Wilson, J. A., J. Chem. Soc., 1916, cix, 307. 
