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160 The specimen employed for experiment may be an intact plant, rooted in a flower pot. It is, however, more convenient to employ cut specimens, the exposed end being wrapped in moist cloth. The shock-effect of section passes off after several hoars, and the isolated organ renews its growth in a normal manner. Among various specimens I find S. Kysonr to be very suitable for experiments on growth. The leaves are much stronger than those of wheat and different grasses, and can bear a consider- able amount of pull without harm. Its rate of growth under favourable condition of season is considerable. Some specimens were found to have grown more than 8 cm. in the course of twenty-four hours, or more than 3 mm. per hour. This was during the rainy season in the month of August. But a month later the rate of growth fell to about I mm. per hour.

I shall now proceed to describe certain typical experi- ments which will show : (1) the extreme sensibility of the Crescograph ; (2) its wide applicability in different investi- gations ; and (3) its capability in determining with great precision the time-relations of responsive changes in the rate of growth. In describing these typical cases, I shall give detailed account of the experimental methods employed, and thus avoid repetition in accounts of subse- quent experiments.

Determination of the absolute rate of growth : Experi- ment 51. — For the determination of the absolute rate, I shall interpret the results of a record of growth obtain- ed with a vigorous specimen 6*. Kysoor on a stationary plate. The oscillation frequency of the plate was once in a second, and the magnification employed was ten thousand times. The magnified growth movement was so rapid that the record consists of a series of short dashes instead of