Page:Collected Physical Papers.djvu/416

396 animal and plant. In both, lowering of temperature slows down the pulsation culminating in an arrest. Rise of temperature to an optimum, on the other hand, enhances the frequency. Diminution of internal pressure causes a similar arrest in both. The rhythmic tissues in animal and plant have a long refractory period. In both, application of external stimulus has no effect during systolic phase of contraction, whereas an extra-pulsation is produced by stimulus during the diastolic phase of expansion. (p. 372).

Records of rhythmic cardiac pulsation were obtained with Resonant Cardiograph which gives the most accurate record of the different rates of movement at different phases of the cardiac cycle (p. 371).

The effects of certain drugs are found to be remarkably similar on rhythmic tissues in animal and plant. Certain drugs thus cause in both a great depression of activity; subsequent application of a particular drug then causes a marked revival of activity.

A considerable portion of this volume deals with the optical properties of electric waves, the study of which has been facilitated by devices for the production of short waves and reliable means for their detection. Results have been obtained which show that electric radiation produces allotropic modification in matter analogous to those by visible light. The most unexpected results are those which demonstrate a continuity of response in the Living and Non-living.

The intricate mechanism of life can only be elucidated by extension of our power of investigation, often in the realm of the invisible. It is only from facts so