Immediately after severe handling of this kind, the retardation of contraction-waves, is sometimes even more marked than here represented; but I think this may be partly due to shock, for on giving the tissue a little while to recover, the rate of the waves becomes slightly increased. Anæsthetics likewise have the effect of slowing the rate of contraction-waves before blocking them. Taking, for instance, the case of chloroform, a narrow spiral strip between one and two feet long was immersed in sea-water containing a large dose of the anæsthetic; the observations being taken at six seconds' intervals, the following were the results:-- [Illustration: Fig 18. Normal water ... Six seconds after transference to chloroform Six seconds later ... Six seconds later ... Six seconds later ... Six seconds later ... One second ... ] In such experiments, the recovery of the normal rate in unpoisoned water is gradual. Taking, for instance, the case of a spiral strip in morphia (Fig. 19), it will be seen that the original rate did not fully return. Some substances, however, exert a more marked permanent effect of this kind than do weak solutions of morphia. Here, for instance, is an experiment with alcohol (see Fig. 20). [Illustration: Fig. 19 In normal water ... Quarter of an hour after exposed to morphia ... One minute after strengthening dose ... Four minutes later, and just before blocking of wave ... Fifteen seconds later, wave continuing blocked ... Immediately after passage of wave on restoration to normal sea-water ... Four minutes later ... Quarter of an hour later ... An hour later ... One second ... ] [Illustration: Fig. 20 In normal water ... Quarter of an hour after exposure to weak dose ... Two minutes after strengthening of dose ... Five minutes later, and just before blocking of wave ... Fifteen seconds later, wave continuing blocked ... Immediately after passage of wave on restoration to normal sea-water ... An hour later ... One second ... ]