When a passive, paralyzed ring is activated by an induction shock, as in figure 7, muscular tonus is at once developed, and irregular and complex contraction waves proceed over it; but the larger waves travel faster than the smaller ones and thus overtake, and combine with them, in this manner forming a single component wave which appears upon the kymograph record as a smooth and regular sinusoidal curve.
All chemicals used in this research were Merck's "Reagent" in quality.
In taking these kymograph records a Jaquet chronoscope beating seconds, or a make-and-break pendulum, was used with each individual line, thus making the accuracy of the record independent of any changes in rate of the kymograph drum. One ascertained the number of seconds required for the contraction wave to travel 100 times around the ring in pure sea-water; and then the number of times it traveled around the ring in the same number of seconds in diluted sea-water gave its percentage rate in the diluted sea-water.
The average temperature of the surface water of the ocean at Tortugas during the day time in June and July is about 29° C.. and the experiments of Harvey (1911), Mayer (1914), and Cary (1916), show that the rate of nerve-conduction augments in practically a right-line ratio from 17.5° to about 36° or 38° when it suddenly declines, the fall in rate indicating injurious effects, possibly due, as Harvey suggests, to the destruction of an accelerating enzyme. For several degrees, both above and below 29°, the rate changes about 4.5 per cent for each 1° C., and this correction was applied to all records. The records in diluted sea-water were usually taken at higher temperatures than those in the pure sea-water with which they were compared. The greatest average range was, however, not more than 1.79° C., but all records were reduced to the rate they would have exhibited had they been taken in a solution at the same temperature as that of the pure sea-water with which they were compared.
Another correction must be made on account of the osmotic inter change between the tissues of the ring and the diluted sea-water in which it is placed. Each experiment was made after the ring had been for one hour in 500 c.c. of fluid and a series of titration with n/10 AgNO,, using as an indicator, showed the osmotic interchange had augmented the concentration of the diluted sea-water as follows: The subumbrella tissue of Cassiopea xamachana is infested with commensal plant cells and thus when pulsating in diffuse daylight it gives out very little free CO,. If placed in the dark, however, the
sea-water surrounding the medusa soon becomes acid, due to the unreduced CO,. All experiments were conducted during daylight hours in the diffuse light of the laboratory, and a series of tests showed that there was no appreciable change in the hydrogen-ion concentration of the pure or of the diluted sea-water after the pulsating ring had been in 500 c.c. of the solution for 1 hour. The laboratory was provided with a Leeds and Northrup potentiometer, which had been standardized by the U. S. Bureau of Standards; also with a Bovie potentiometer and two sets of standardized colorometric tubes made by Hynson, Westcott, and Dunning, one set being that of Rowntree, Levy, and Marriott, and filled with phenolsulphonephthalein, and the other set that of McClen don, wherein the tubes are filled with graded solutions of thymolsul phonephthalein. Both these sets of tubes were standardized by Pro Minor McClendon, who was engaged upon a study of the sea-water as a physiological fluid. He found that the P. of the surface sea-water at Tortugas in summer, at about 29° C., ranges from 8.1 to 8.2, the range being due to variations in its carbonates. As is well known from the studies of L. J. Henderson (1913), these carbonates act as a buffer substance, and by ionizing they tend to neutralize the effects of any slight accession of acid to the water. Thus McClendon found that sea-water of P. 8.1 diluted with an equal volume of distilled water of P. 6.04 gave a solution of P. 8.09. Also 50 per cent sea-water plus 50 per cent distilled water of P. 8 gives a solution which is fully as alkaline as, if not slightly more so than, pure sea-water.
A number of testa of the change in hydrogen-ion concentration after pulsating rings had been in 500 c.c. of various dilutions of sea-water showed that in daylight there was no considerable change in 1 hour; while in four others it declined similarly in pure sea-water after 12 hours, and in 3 other rings placed for 12 hours each in 500 c.c. of 60 per cent sea-water plus 40 per cent of 8 P. distilled water the P. had declined to 7.95. The average change at the end of an hour was certainly not greater than from 8.1 to 8.0 P.