and the remaining marginal body in the other portion, etc. Yet, although it was very exceptional to find the two portions presenting an equal degree of endurance, no uniform results pointing to the cause of the variations could be obtained. In most cases, however, the energy, as distinguished from the endurance of the larger segments, was conspicuously greater than that of the smaller. (But it is curious that in many cases the effects of _shock_ appeared to be more marked in the larger than in the smaller segments--the latter, for some time after the operation, contracting much more frequently than the former.) To show both these effects, one experiment may be quoted. A specimen of Sarsia was divided into two parts, of which one was a quadrant. Immediately after the operation the results were as follows:-- ----------------------++---------------------- Portion 1/4. || Portion 3/4. ------------+---------++------------+--------- Number of | Minutes || Number of | Minutes pulsations | of rest || pulsations | of rest ------------+---------++------------+--------- 20 | 0 || 0 | 5 4 | 4 || 10 | 2 15 | 5 || 46 | 1 6 | 3 || 23 | 2 ------------+---------++ 49 | 1 45 | 12 || 900 | 1 | || 117 | 1 ------------+---------++------------+--------- || 1145 | 13 ----------------------++------------+--------- To show the difference between the _endurance_ of two halves of a bisected specimen of Sarsia, I may quote one experiment which was performed on the same specimen as the one mentioned in the text to show the general relationship between the duration of the pauses and that of swimming bouts. (See last footnote.) Immediately after bisection. ----------------------++---------------------- 1/2 A. || 1/2 B. ------------+---------++------------+--------- Number of | Seconds || Number of | Seconds pulsations | of rest || pulsations | of rest ------------+---------++------------+--------- 56 | 10 || 82 | 180 150 | 150 || 51 | 20 68 | 335 || 14 | 60 130 | 30 || 13 | 50 46 | 45 || 46 | 45 2 | 10 || 38 | 65 99 | 66 || 18 | 45 103 | 360 || 23 | 60 12 | 4 || 35 | 130 ------------+---------++ 105 | 70 Pauses now become || | longer, and swimming|| | bouts shorter. || | ----------------------++------------+--------- Twenty-four hours after the operation.