RESPIRATORY METABOLISM OF PLANARIA AGILIS. 



217 



of fifty animals in each lot were used. Six bottles were filled 

 with CO 2 -free air while another lot of six bottles were filled with 

 hydrogen. The CO 2 produced by the worms in two bottles from 

 each of the series filled with air and hydrogen respectively was 

 determined at the end of 5, 10 and 15 hours, as shown in the 

 table. The amounts of CO 2 produced during each one of the 

 successive periods of five hours in air was 0.57 c.e., 0.87 c.c., 

 0.69 c.c. CO 2 ; and in hydrogen 0.73 c.c., 0.62 c.c. and 0.75 c.c. CO 2 . 

 The lots of fifty worms each were of course selected carefully as to 

 size, history, etc., so as to render them comparable. The table 

 shows clearly that no marked difference in the rate of CO 2 

 elimination occurs in the animals in air and those without free 

 oxygen. All animals were normal at the end of the experiment. 

 Table VII. is a similar experiment of longer duration. The 



TABLE VII. 



Planaria starved and kept at 20 C. n daj's before the experiment. Temperature 

 during the experiment 19.5 C. Twenty- five worms were placed in each bottle 

 in 2 c.c. water. Blanks run as controls are not given in the table, i c.c. 

 N/ioo HC1 equivalent to o.m c.c. COs. 



carbon dioxide elimination during the successive four periods of 

 seven hours each is in air 0.80 c.c., 0.95 c.c., 1.47 c.c., 0.95 c.c., 

 while in hydrogen it is 0.64 c.c., 1.06 c.c., 1.27 c.c., 0.21 c.c. A 

 comparison of the condition of the animals at the end of the 7-, 14- 

 and 2i-hour periods showed all the animals in hydrogen to have a 

 normal response to light and touch. While at the end of twenty- 



