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. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AUGMENTATION PHENOMENA IN THE EARTHWORM 307 acetylcholine and which was antagonized by physostigmine. This he thought was probably a high concentration of choline esterase. If acetylcholine is produced by stimulation of the earthworm muscle preparation, and if this is not completely hydrolyzed by choline esterase before the next stimulation, the persisting acetylcholine could be the cause of the augmentation of the responses. The application of phy- sostigmine which prevents the action of choline esterase could, therefore, s

. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AUGMENTATION PHENOMENA IN THE EARTHWORM 307 acetylcholine and which was antagonized by physostigmine. This he thought was probably a high concentration of choline esterase. If acetylcholine is produced by stimulation of the earthworm muscle preparation, and if this is not completely hydrolyzed by choline esterase before the next stimulation, the persisting acetylcholine could be the cause of the augmentation of the responses. The application of phy- sostigmine which prevents the action of choline esterase could, therefore, s Stock Photo
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. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. AUGMENTATION PHENOMENA IN THE EARTHWORM 307 acetylcholine and which was antagonized by physostigmine. This he thought was probably a high concentration of choline esterase. If acetylcholine is produced by stimulation of the earthworm muscle preparation, and if this is not completely hydrolyzed by choline esterase before the next stimulation, the persisting acetylcholine could be the cause of the augmentation of the responses. The application of phy- sostigmine which prevents the action of choline esterase could, therefore, show some effect upon the augmentation phenomenon. The following experiments were devised to test this hypothesis.. FIG. 7. Effect of physostigmine, 1 gm./10,000 cc., on the responses of muscle strip to a series of bursts of stimuli. Interval between bursts, 27 seconds. Fre- quency, 40 shocks per second. Drum stationary. A, physostigmine applied by drip method during experiment. B, muscle strip immersed in physostigmine for 15 min- utes previous to stimulation. The effect of physostigmine on the responses to a series of single shocks was to produce a striking augmentation. The whole worm preparation was stimulated for 5 seconds at a low frequency of 7 shocks in 5 seconds. This was followed by a 3-minute period of rest during which the preparation was given Ringer's solution by drip method. Figure 6, A shows a series of five of these 5-second stimulations. Within each of the five groups there is an increase in the successive responses, but the facilitation decays during the 3-minute rest period, so that the first response in each of the five groups is of the same magnitude. Figure 6, B shows the result of repeating this procedure except that physostigmine drip 1 gm./10,000 cc. was substituted for the Ringer's. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustration