1918] Michael: Behavior of Salpa democratica 277 



As in table 11, each of the four conditions deduced from the loco- 

 motion theory appear in this table : 



1. The frequencies of the two generations are identical in the two 

 lowest temperature groups, nearly identical in the highest temperature 

 group, and parallel throughout. The frequency of both generations 

 decreases as the temperature increases from its lowest to its middle 

 value (18?4C-19?5C), and then increases. 



2. The frequency of both generations is greater in the coldest than 

 in the warmest water, and also greater in the next coldest than in the 

 next warmest water. 



3. Abundance of aggregate forms parallels frequency of both gen- 

 erations, decreasing from a maximum (945 per hour) in the coldest 

 water to a minimum (115 per hour) in water between 18?4C and 19?5C 

 in temperature. 



4. Solitary forms increase in abundance from 54 to 72 to 112 to 334 

 per hour as the temperature increases from its lowest to its highest 

 value. 



In table 13 the data are once more retabulated relative to five 

 temperature groups according as the temperature lay between 15?9C 

 and 16?9C, 17?0C and 17?9C, 18?0C, 18?9C, 19?0C and 19?9C, or 

 20?0C and 20?8C. Be it noted, that although the lowest group has a 

 range of 1?1C and the highest a range of 0?9C, the range of each of 

 the three middle groups is one degree. 



Table 13 



Surface distribution of Salpa democratica during June and July, 

 1908 and 1909, relative to five temperature groups 



Once again are eacli of the four conditions deduced from theory, 

 revealed : 



1. The frequencies of the two generations are identical relative 

 to the three lowest temperature groups, and decrease as the tempera- 



