6o 



C. M. CHILD. 



long persistence of pulsation in both members of the pair in 

 Series 5, VI. (HC1 w/65o) as compared with the other series is 

 anomalous and no reason for it is known. Otherwise the data 

 in the table are consistent and show that for the concentrations 

 included, except m/i^oo, the young animal is more susceptible 

 than the old. 



Results with KNC show similar relations between age and sus- 

 ceptibility, of course with much lower concentrations. The 

 results of one series on pulsation susceptibility are given in 



Table VI. 



TABLE VI. 



Mitrocoma: SUSCEPTIBILITY OF PULSATION TO KNC. 



In the first pair, 4, IV., w/iooooo, the susceptibility is shown, 

 not in the 'time of cessation of pulsation, but in the retardation 

 of the rate. At the beginning of the experiment rate A = 2, 

 rate B approximately, but after five hours rate A = Y% rate B. 

 In the second pair, 4, III., W/SOOGO, pulsation in the young animal 

 is almost completely inhibited after 5^/2 hours, while in the old 

 it is still strong. Here rate A was very much lower than rate B. 

 In the higher concentrations pulsation ceases in a few minutes. 



A few experiments with other agents give similar results. In 

 neutral red animals 18-20 mm. long cease to pulsate, undergo 

 shrinkage and begin to disintegrate much earlier than animals 

 60 mm., although no marked difference in rate or intensity of 

 staining is apparent. In methylene blue 1/30000, increased to 



