Plate A with which the salt tests described in the previous pages were made. With reference to the hydrogen ion concentration the solution of salts added to the agar had a PH value of about 5.8 to 6, the agar alone being about 6.5.

The salted agar showed a swelling in even the attenuated solutions of calcium and magnesium chloride less than in water. Such solutions accelerate swelling in pure agar. The swelling of the salted agar in sodium solution was as 102 with water at 100, while that in the potassium solution was 132. That this inequality is not simply a matter of hydrogen ion concentration is evinced by the fact that the swelling in the acid at PH 4.2 was practically equivalent to that of the potassium chloride at 5.7.

The incorporated solution may be regarded as approximately balanced and when the sections were swelled in a similar solution the maximum of the series was reached, the increase being as 150

to water as 100.

An identical solution was used in making up "Bacto-gelatine and the results of the hydration of sections of the dried plates are as in Table VII.

Hydration of gelatine plate made up gelatine 5 g., 10 c.c. KC1 at 0.01 M, 6 c.c. NaCl at 0.001 M, and CaCl2 10 c.c. at 0.0001 M, and water 25 c.c. at 14° C. Sections 0.24 to 0.26 mm. in thickness.

It is to be recalled that this gelatine had a Ph value of 5.2 and that the incorporated salts a Ph of about 5.8 to 6, so that when the dried sections were placed in a salt solution of this constitution the swelling was less than in water and that a similar decrease was noted in the calcium and potassium solutions in 0.0001 M and 0.001 M solutions and in the calcium solution at 0.01 M also. Increases

took place in the potassium solution at PH of 6.6 and in the acid at PH of 3 and 2. It is evident, without a detailed analysis of these results, that many features beside hydrogen ion concentration are involved.

All of the foregoing tests had as their chief purpose the determination of the reactions of plasmatic constituents and the experiments were extended to include the swellings of a biocolloid including both pentosans and gelatine with the addition of salts, but without the third colloidal component, the soaps, which we now have ample reason to believe play a very important part in the mechanism of living matter. A mixture of gelatine 3 parts and agar 2 parts was made in the usual manner with the addition of salts as in the preparations of agar and of gelatine separately. The increases when hydrated in various solutions were as noted in Table VIII.

The more prominent reactions are those of the gelatine element as would be expected in accordance with which the highest concentration is in the most concentrated solution of the acid. It is notable that as in the gelatine-agar salt-free plate depression occurred in acid at PH 3 and that at PH 4.2 the swelling was still below that of water. Practically applied to the living cell this would mean that hydration lessened with increasing acidity to the region of PH 3 beyond which the active cell would rarely go. Sodium and calcium exerted similar effects, but the swelling in potassium at 0.0001 M was equivalent to that in water while at 0.001 M it was greater. A review of the results presented in this paper would show many special results from the action of this salt.

The recently published results of experiments upon the coagu

lating action of neutral salts upon plasmatic colloids by Tadokoro furnish some important collateral conclusions. Tadokoro found that all chlorides of aluminium, barium, strontium, calcium and magnesium cause coagulation of plasmatic colloids in an increasing series in the order given in concentrations from N/200 to N 10, and that KCl exerted a stronger action than NaCl. Many profitable comparisons may be made between the results of his tests of the action of salts upon crushed galls and of the swelling reactions of biocolloids given in the present paper. Furthermore both afford many parallels with the swelling reactions which were obtained by the extension of my experiments to include the measurement of the action of the salts, particularly the chlorides, upon living and dead cell-masses.

The first material tested was taken from the large "prop" roots of corn plants a meter in height growing in the garden at Carmel. Root-hairs were only sparingly developed on a terminal section 3 to 5 cm. long, and sections 4 or 5 mm. in length including the tip were taken and freed as completely as possible from particles adherent from the loose sandy soil in which they grew. The average thickness of trios placed under the auxograph ranged from 2 to 2.5 cm. Such sections dried down to thickness of 0.3 to 0.4 mm. when placed between sheets of blotting paper.

Such sections of living material made practically all of the changes in volume indicated within eight to fifteen minutes, the speediest action taking place in the acid and the slowest recorded being in the potassium solution, although this matter is partly a function of the size or length of the sections. In illustration of the swelling and shrinkage it may be cited that in the acid the sections return to normal size in about 2 hours. Shrinkage to original thickness may in some cases take place within a day, although twice this period elapses in other instances.

The results of the auxographic measurements are given as average percentages of original thickness in Table IX.

If the facts in this table are taken for comparison with those

8 Tadokoro, T., "Kolloidchemische Forschungen ueber das Pflanzenplasma," Jour. Coll. of Agric., Hokkaido Imp. Univ., Sapporo, Japan, 7: part 5, 144-182, 1919.

obtained from the salted biocolloid, disregarding possib.e osmotic effects, it will be seen that hydration in both potassium and sodium is greater than in water, magnesium equivalent, the swelling less in calcium and acid, indicating that the cell-colloids are dominantly

TABLE IX.

HYDRATION OF ROOTS OF Zea mais, LIVING ANd Dried, at 15° C.

pentosans. The dried and dead material showed increased hydration capacity over water in all solutions except that of calcium, measurements which may be taken to be free from the major part of the errors introduced by the osmotic and plasmolytic effects in the living material. It is notable also that when calcium was balanced with sodium the swelling was at a minimum in the living material but it rose above that in water in the dried cell-masses, but did not attain the maximum value for the series which was shown by the calcium solution at 0.0002 M. The dried material presents a series of hydration reactions which suggest those of an agar-gelatine mixture.

The smaller actively growing roots of the same maize plants were subjected to comparative tests in a living condition only. Swelling was most in acid and least in water, the series being water

NaCl, balanced solution, CaCl,= KCl, HCl, as contrasted with the larger roots in which the series was CaCl2, balanced solution, HCI, KCl, and NaCl as given in Table X.

Seeds furnished by Dr. Fawcett, of the Citrus Experiment Station at Riverside, California, were sprouted in a chamber at 23° to 25° C., by being placed in a moist sand bed. When the roots had attained a length of 1 to 3 cm. the apical portions 3 or 4 mm. in

TABLE X.

HYDRATION OF SMALL MAIZE ROOTS IN VARIOUS SOLUTIONS AT 15° C.

length were cut off, placed in trios in glass dishes, covered with a triangular sheet of glass from which bearings were taken by auxographs in a room at 15° C. The swellings in percentages of original thickness were as in Table XI.

The series at 0.01 M was HCl, NaCl, KCl=balanced solution, sea-water, water. In the more attenuated solutions the series was HCl, NaCl, CaCl2, KCl, sea-water, water, balanced solution, only the last named producing a hydration greater than in water. The series is suggestive of the action of a dominantly pentosan biocolloid.

Some plants of Fragaria (strawberry) which were growing in an injuriously saline soil were transferred to a sand bed and roots grown in both sub-strata were available for testing. The differences which might be induced by these divergent factors are well illustrated by the measurements given in Table XII.