196 



ANIMAL AGGREGATIONS 



manner as possible. After the respiration chambers were closed, 

 they were placed side by side in running water and were thus exposed 

 to identical conditions during the respiration period, which usually 

 lasted for i hour. The isopods from each series were brought into 

 the laboratory, where their moist weights were determined. The 

 results obtained are summarized in Table XVII. The figures on 

 oxygen consumption and weight are mean results from the number 

 of groups indicated in the first column, or from the same number of 

 isolated individuals as were tested in the groups. 



TABLE XVII 



Showing the Amount of Oxygen Consumed by Groups of 10 Male Isopods during 



Their First Hour after Removal from a Large Bunch, as Compared with 



A Similar Number of Animals That Were Isolated When Collected 



* Last test ran 2 hours. 



Twenty-five comparable tests were run with or without correcting 

 for weight. The set of lo isopods that had previously been scattered, 

 in all cases but two, used more oxygen during the respiration period 

 than did the set of the same number taken from the aggregation and 

 started at almost the same time. Always the total amount of oxygen 

 consumed by all the members of one series of animals that had been 

 scattered was greater than that used by the series from the aggre- 

 gated isopods run at the same time. 



Without correcting for weight, the mean difference in oxygen con- 

 sumption in these live different series shows that those that were 

 soHtary when collected used 12.33 cu. mm. more oxygen during the 

 first hour's exposure in a respiration chamber than those that came 

 from the aggregation. Apphcation of Student's statistical method 

 shows that there is less than i chance in 100 of getting so great a 

 deviation in either direction from the mean in random sampling. 



