WATER-BEARS AND ROTIFERS. 



85 



ordinary fact about them. They, like some Rotifers, 

 are so extremely tenacious of life that they will 

 bear drying up into (to all appearance) fine dust, 

 and in this condition are carried hither and thither 

 by the wind ; and so their being in the roof-gutter 

 is accounted for. Here they lead a fitful and inter- 

 mittent life of activity and repose, according to the 



FIG. 14. Water Sear (after Slack). 



fluctuations of the weather at one time dry as dust 

 and scorched by the sun, and at another active in 

 sentient life under the refreshing rain. It may be 

 presumed that they would rather be always in the 

 water ; but ponds as well as gutters sometimes dry 

 up. So they have in the course of ages accommo- 

 dated themselves to these inevitable fluctuations, 

 and are apparently well content with their present 

 lot. Not much water, however, is necessary to 

 their active existence ; for they are often found 



