140 The Ohio Journal of Science [Vol. XVIII, No. 4, 



the regular feeding time. Owing to inconveniences in obtaining 

 the subjects at definite times of the day, it was impossible 

 to work with them at stated intervals before and after feeding. 

 But had the penumographic curves been taken at definite 

 times and alike for each subject, the above fact would probably 

 have been illustrated more clearly, and would have shown that 

 each individual possessed a cycle of nervous activity, being 

 greatest at feeding, diminishing after feeding and continuing 

 to diminish until the before feeding condition was reached, 

 and then gradually increasing in nervous activity again until 

 the feeding condition had been reached, when it would be at 

 its height, and then this cycle would be repeated as the next 

 feeding time approached. Each animal of course would have 

 a definite point, which would be characteristic of that individual, 

 at which point the nervous activity would begin to increase or 

 decrease, depending on the nervous make-up of the animal in 

 question. The times at which these tracings were made are 

 different, but the attempt was made to choose approximately, 

 a definite time, in so far as existing conditions would permit. 



A general comparison of all the composite polygons men- 

 tioned may also be made. It will be seen that each individual 

 has its own characteristic polygon, and that each is distinctly 

 different from that of any other. Those of Seven H appear 

 rather long and narrow. (It will be noted that all the polygons 

 are plotted to the same scale.) Those of Three H are shorter 

 and broader and more irregular, while the polygons of Two H 

 are still shorter and broader and rather flat, with about the 

 same amount of irregularities as those of Three H. Lastly, 

 those of Five H are the most irregular of the four and do not 

 show much symmetry, but are spread over the entire width of 

 the page. Thus each animal shows its individuality in its 

 respiration polygons, even under three different conditions, and 

 the peculiar conformations and variations are distinctly char- 

 acteristic of this one individual and not of any of the others. 

 All of the composites seem to possess a common feature, namely: 

 the shorter amplitudes show a higher frequency than those of 

 extreme length; in other words, the long respirations do not 

 occur as often as the short ones, which gives the polygons 

 an abrupt slope to the left and a more gradual slope toward 

 the right. 



