DIVISION RATE IN CILIATE PROTOZOA. 



311 



A curve plotted from the averages of all five of the different 

 experimental lines and drawn beside a curve portraying the 

 averages of the control lines for the same periods, each figured 

 day by day for the six days, represents, in a manner, a generalized 

 curve of the effect of vertebrate thyroid constituents on protozoa, 

 as based on our data. This curve takes the following form: 



Day 123456 



Chart 6. A curve plotted from the averages of Charts i, 2, 3, 4 and 5, and thus 

 representing a composite of results obtained from use of thyroids from each of the 

 five main classes of vertebrates. 



Discussion. 



The number of papers which have hitherto been published 

 along this line seems to be limited to those already mentioned; 

 so that conclusions have to be drawn from a comparatively 

 meager literature, and to gather largely around the investigator's 



