No. 628] HABITAT RESPONSES OF WATER-STBIDER 405 



channel of the brook. They first tried one path and then 

 another. These trials resulted in bringing some of the 

 gerrids to the . pool, but with reference to other water- 

 striders the trials were not so successful. I found that it 

 was a rather strenuous task to watch all the gerrids, 

 although some of them freciuoutly would come to rest. 

 Without giving too many details, it may be stated that all 

 of the eight individuals, already mentioned, made their 

 way in a blundering fashion to the large pool of water. 

 The first one reached the pool in 5 minutes and 30 seconds, 

 and at once moved on to the surface-film. The time re- 

 quired by the others to I'cncli the water varied to a con- 

 siderable extent, the aNci'aiic 1mm iii-' 14 mi mites and 30 

 seconds. The last in(li\l(lual, of the uroiip ol* eight, to 

 reach the pool was lil'leeii miinitrs in luakiiiu- llic journey. 

 Three gerrids out of the eight iraNcrxMl ihr (ristaiici' to 

 the pool wdth only a limited iniiiilx'i- ot st(»p> .-iiid na- 

 tions from the straight path. 1 1(»\vc\ cr. this i> noi to 

 say that the journey was free I'l-diii ci-ralic iiiox cmciits, 

 on the part of these iii>eri^. Tor ^ncii wa^ not the raM'. 

 The stops usually oct-iin-ed wh.'n Ihe uvi-i-ids (•;inie in 

 contact with >ouw (.h-; :!<•!,■ in their n.-Mh,. h i;ot at 



all uncommon, uhen th.- in^.vt^ nmxrd .-iNvay tVnm th.-ir 

 stopping ])la('e, I'or the dii-eetion ol hx-ouK ition to he 



