tration of the latter is much lower. This observation agrees with the observations of former investigators on the relative rates of penetration of strong and weak bases.

The viability of Valonia in these various solutions is given in Table I. This shows that NH,OH is the most toxic of the substances used, and that NHC is more toxic than (NH),SO,. The slower rate of penetration of the sulphate ion has probably some influence upon the degree of toxicity. This is of interest when compared with the results obtained by the writer in the study on acids, in which it was found that HCl is more toxic than H,SO,, and also that sulphuric acid has a slower rate of penetration than hydrochloric acid.

With ammonium salts it was found that the pH of the sap before removal of free NH,, as represented by curves C, never exceeded that of the solution in which the cell was placed. This may be contrasted with the case of concentrated solutions of NH,OH in sea water, which was sufficiently alkaline to call into play a buffer mechanism in the sea water but not in the sap, and as a consequence allowed the pH of the sap to exceed that of the outside solution. When cells which had been placed in solutions of NH,OH in sea water were again placed in pure sea water, the time required for the sap to regain its normal pH was about two or three times as long as that necessary for the original change in the opposite directions.

In order to determine whether the penetration of the Na ion was affected by the OH ions, two other types of solution were tested: one a solution of Na silicate in sea water (pH 9.3), and the other a solution of Na butyrate in sea water (pH 7.9). The same molecular concentration was used for these solutions as for the hydroxides. Na silicate undergoes hydrolytic dissociation to a considerable extent. There was no change in the pH of the sap after 3 hours in this solution. Presumably neither sodium nor silicate ions penetrated. In the case of Na butyrate, hydrolytic dissociation also occurs; but it might be thought that in this case, since the butyrate ion enters so readily (5), the Na ion also would enter. No change in the pH of the sap took place within 18 minutes. After 27 minutes, however, the pH became 7.5; but there was by this time decided injury of the cell, which cytolyzed when taken out and placed in sea water. It seems that in this case the butyrate ion entered without or with very little Na. These experiments agree in showing that Na has little. penetrating power at any H ion concentration within the pH range 7.9 to 12. It is apparently the impermeability to Na which excludes NaOH from the cell sap. In the case of NH,OH, it was not possible to determine whether penetration of the whole molecule. takes place or only of the NI,.

DEAD CELLS.

When dead cells were placed in solutions of the salts of ammonium used in these studies, their sap rapidly assumed the pH of the surrounding solution: (NH),SO1, pH 7.5; NH,Cl, pH 7.8; and (NH,)2CO3, pH. 7.8 (illustrated in Table III). When the expressed sap from dead cells previously exposed to these solutions is placed in Pyrex tubes and aerated by CO2-free-NH,-free air, the pH of the resulting sap becomes, respectively, 5.2, 5.2, and 8.8. These values are the same as those assumed by the solutions of these salts in sea water when they are aerated in the same way. In the case of the sulphate and chloride, the acidity is due to the nonvolatile acid left behind, and in the case of the carbonate, to the nearly complete removal of both ions. Both the sap and the solutions were aerated for from 4 to 5 hours, at the end of which time further change had practically ceased.

TABLE III.-pH of sap of dead cells of Valonia and of surrounding solution before and after aeration with compressed CO2-free-NH3-free air. Cells were 30 minutes in solution.

These experiments further corroborate the theory that the internal Hion concentration of a cell is not determined primarily by that of the surrounding solution, but that the relative H ion concentration of the sap and the environing fluid may be profoundly affected by the nature of the acid or basic radicals present. This is emphasized by the comparable experiments on NaOH and NH,OH, which had practically the same H ion concentration and yet had decidedly different effects upon the pH of the sap of Valonia.

Although some writers have called attention to the importance of other than I ions, the importance of the H ions seems to have been quite often overestimated. Before definite conclusions as to the in

fluence of H or OH ions can be stated, the effects of the chemical nature of the accompanying anions or cations must be determined.

The great permeability of Valonia to CO, and NH, or their derivative ions raises some interesting questions. The case of ammonia is particularly interesting, since Vanzetti (14) has shown that when an ammonium salt in aqueous solution is allowed to diffuse against gravity, the acid radical travels more rapidly than the base, and is in excess in the forefront of diffusion. This finding is in accord with the migration velocities of the ions as determined by the method of transference numbers. Yet when NH,Cl, for example, passes through the cell wall and the protoplasm of Valonia, the basic radical penetrates with very much the greater rapidity: the cell sap becomes alkaline and ammonia is found to be present in it. In the case of carbon dioxide the anion penetrates with a relative rapidity strikingly in excess of that which would be predicted from the transference numbers.

It will be evident that in trying to account for these differences we must look for distinguishing features-presumably chemicalin the behavior of the two ions concerned, which would place them in peculiar relationship to the protoplasm. Two possible explanations are of particular interest: One is based upon the pseudo-acid and pseudo-basic characters of CO, and NH,, and the other upon the possibility that they may exist in solution in the form of dissolved gas molecules.

In the latter case we would have to consider the passage of particles which are electrically neutral, and might, for this reason, more easily pass through the wall and protoplasm. Such particles would presumably carry relatively little water of hydration, which would give them additional facility of penetration.

The explanation based upon the pseudo-acid or pseudo-basic nature of the substances in question has been suggested by Loeb (15), who explains the accelerating effect of sodium acetate upon the penetration of acetic acid into Fundulus eggs as the result of an increase in the tautomeric or "aci-" form of the acid. This form is considered to be capable of penetrating the cell with some ease. The same possibility of transformation into an "aci-"form exists for carbonates and ammonium compounds; and it may be supposed that for this reason Valonia and other forms are particularly permeable to these "aci-"tautomers.

The penetration of acids, bicarbonates, alkalies, and ammonium salts depends at least in part, then, upon the chemical nature of the ions present. For this reason it is interesting to note the fact, expressed by Loeb (13) (p. 707) that on the acid side of the isoelectric point, "the effect of salts on the membrane potentials, osmotic

59160°-23-3

pressure, swelling of gelatine chloride, and that type of viscosity which is due to the swelling of protein particles, depends only on the valency and not on the chemical nature of the anion of the salt."

By analogy with the experiments of Loeb, one might reasonably inquire whether those properties (swelling, viscosity, etc.) which depend only on the valency of the ions present have anything to do with the regulation of permeability. Certainly in the case of Valonia the chemical nature of the ions plays the determining part.

SUMMARY.

1. Ammonium salts (NH,CI, (NH,),SO,, and (NH,),CO, and NH,OH cause an increase in the pH value of the sap of Valonia. This increase is due to penetration of free NH,, which may be removed by aeration of the sap with NH,-free air.

2. Increased acidity of the NH-free sap, presumably due to the penetration of anions, was observed to be greater in the case of chlorides than in the case of sulphates.

3. Both ions of (NII,),CO, penetrate and can be removed by acration, the CO, being more rapidly removed than NH,.

4. Different concentrations of NH,OH having the same pH in sea water may produce different pH values of the sap.

5. KOH penetrates very slowly but still slightly faster than NaOH. 6. The sap of dead cells assumes the same pH value as the solutions in which they are placed. Their aerated sap has a pH value equivalent to the pH after aeration of the solutions in which they are placed.

Acknowledgments.-The writer takes pleasure in acknowledging the courtesies afforded by the Miami Aquarium Association where this work was done, and in expressing much gratitude to the authorities of the Carnegie Institute of Washington, who made arrangements for collecting the plants.

REFERENCES.

(1) Warburg, O.: Zeit. f. Physiol. Chem., €6, 305; 1910.

(2) Harvey, E. N.: Publication No. 183, Carnegie Institute, Wash., 131-146; 1914.

(3) Osterhout, W. J. V.: Jour. Gen. Physiol., 4, 275; 1922.

(4) Brooks, M. M.: Jour. Gen. Physiol., 4, 347; 1922.

(5) Brooks, M. M.: Pub. Health Rpts., 38, 1449; 1923.

(6) Atkins, W. R. G.: Jour. Mar. Biol. Assoc., 12, 717, 772, 781, 785, 789, 91; 1922.

(7) Hoagland, D. R., and Davis, A. R.: Jour. Gen. Physiol., 5, 629; 1923.

(8) Brooks, M. M.: Proc. Soc. Exp. Biol. Med., 1922, xx, 39.

(9) Crozier, W. J.: Jour. Gen. Physiol., 1, 381; 1919.

(10) Atkins, W. R. G.: Jour. Mar. Biol. Assoc. Unit. Kingd., 12, 789; 1919-22.

(11) Jacobs, M. H.: Jour. Gen. Physiol., v, No. 2, 181; 1922.

(12) Brooks, M. M.: Pub. Health Rpts., 38, 1470; 1923.

(13) Loeb, J., and Kunitz, M.: Jour. Gen. Physiol., v, 673; 1923.

(14) Vanzetti, L.: Koll. Zschr. ix, 54, 1911.

(15) Loeb, J.: Jour. Gen. Physiol. v, No. 2, 231, 1922.

THE AMERICAN DIETETIC ASSOCIATION TO MEET IN

OCTOBER.

The American Dietetic Association will hold its sixth annual meeting at Indianapolis on October 15, 16, and 17.

Among the speakers will be the following:

Mrs. Octavia Hall Smillie, president of the association.
Miss Effie Raitt, University of Washington.
Dr. Russel Wilder, Mayo Clinic.

Dr. A. C. Clowes, Eli Lilly Co.

Dr. Ruth Wheeler, University of Iowa.
Dr. Louis Burlingham, Barnes Hospital.
Dr. Amy Daniels, University of Iowa.
Mrs. Gertrude Gates Mudge, and

Miss Lydia Roberts, University of Chicago.

The program will cover every phase of applied dietetics.

DEATHS DURING WEEK ENDED AUGUST 25, 1923.

Summary of information received by telegraph from industrial insurance companies for week ended August 25, 1923, and corresponding week of 1922. (From the Weekly Health Index, August 28, 1923, issued by the Bureau of the Census, Department of Commerce.)

Deaths from all causes in certain large cities of the United States during the week ended August 25, 1923, infant mortality, annual death rate, and comparison with corresponding week of 1922. (From the Weekly Health Index, August 28, 1923, issued by the Bureau of the Census, Department of Commerce.)

1 Annual rate per 1,000 population.

5,935

10.6

10.7

884

953

20

5.0

5.5

32

14.2

15.3

61

14.3

15.6

164

11.1

11.8

4

59

6

5

Deaths under 1 year per 1,000 births-an annual rate based on deaths under 1 year for the week and estimated births for 1922. Cities left blank are not in the registration area for births.

Deaths for week ended Friday, Aug. 24, 1923.