PHOTOTACTIC RELATIONS IX THE MAY-FLY. -~I 



cent., tartaric .04 per cent., nitric .03 per cent., sulphuric .03 

 per cent., boracic .05 per cent., and acetic .07 per cent. Similar 

 n -ults were obtained with the salts, although the number of 

 -prrimrn> which became positive- \va- xuiu-uhat Miialler. Ho\\- 

 ever, all tin- >alt- employed H'frrtrd a re-version, and the con- 

 centrations necessary to do thi- are as follow-: pota--ium iodide 

 .3 PIT cent., pota iiim chloride- .3 prr ci-nt., ammonium bromide 

 .3 prr cent., -odium chloride .3 per cent.. >odium Milphite .06 

 PIT cent., and -odium -ul|>hai>- .08 prr cent. 'I'lu- alkalic- were 

 less effective, only about hall" of tin- -prrimrn- becoming po-iiivc 

 in tln-r -oluiinn-. In general all of tin- -prrimrn- U-ramr quite 

 inarti\r, and uhni -pi-i iiiu-n- \\hich faili-d to manifest a po-iii\- 

 n->|ion-i- urn- plan-d in ihr^riid of tin- ba>in nraiv-t ID thr li^lil, 

 tin \ -rldom mailr an\ rl'fort to -ct au Ml tlirrr of thr 



alkali.-, -odinin h\<lro\idr. |)ota--ium h\dro\idr, and ammonium 

 li\dio\idr, uhi(h were rmplo\r<l. produii-d -imilar rr-ull- at 



about the same concentration, which was ,09 per cent. Alcohol. 



too. at a ( OIK ( iniaiioii of about .8 prr cent, produced a iv\rr-al 

 ol thr ivarl!..|) in a lar^r perCCnl 1 hr -prcilllrll-,. 



Ill lllrii Mallir.ll rll\ innimrllt tllr-r inseCtS li\r on lllr Ulldrr 

 side ol Stones and r\ni in thr a.|iiaria I lia\r m\ i tin-in on 



llir llppri- surl \\ in n a i n tain amount of an\ of thr above 



mmiioiird rhrmir.iU ua- addrd to thr \\aliT ill thr ai|liaria. 

 thr n\ n 1 1 ill- \\ould -o. .n ( T.IU 1 up on to|i. 1 e acids, a^ain. \\rrr 

 pan i< ulail\ rllrcii\r iii tin- change, and although ordinarx da\ - 

 liljll Ua- -lllticirilt lo brill;^ lllr ll\lll|>h- UJ). lllr I>-lllt-> brraillr 

 nioi, ob\ ion- uhrn llir aquaria u rrr taken in the dark room and 

 a -lion- liijit ua- -u-prlidtd OVCf thrill. 



It ;^i\r- nir ]>lra-urr here \ ackllouln|-r m\ indebt I'd lle-^ to 

 Trof. s. |. llolmr-. for hi- hrl|> .ind kindly critici-m-. 



I vi -u \ lkV. 

 I M\ i k-i iv ..i \\ i-. . INSIN. 



