Sheldon, Reactions to Cliomcdl Sitimili. 285 



SIGNS AND ABBREVIATIONS USED IN THE TABLES. 



Numbers at the heads of columns refer to the points stimulated as shown 

 on Figs. 1 and 2. Other numliers indicate the reaction time in seconds. 



— is equivalent to the word to. 



* signities (hat a reaction wiis secured with the region stimulated out of 

 water, according to some of the methods already descrilied. The reaction 

 time in such cases was rarely taken. The exceptions are indicated by the 

 rei>lacement of — by *. 



I refers to cases in wliicli tlie reaction was secured with the region tested 

 under water, the reaction time not being taken. This sign usually signifies 

 that the reaction was very weak and incomplete. 



X is used in one case where the reaction was very strong and definite, 

 but where the reaction time was not taken. 



indicates that no reaction could be secured with the fish, either under 

 or out of water. When used after another number it signifies that no 

 reactions were secured in two or three of the five tests made. 



Where blank spaces occur no tests were made. 



Am. and Sod. trier., ammonium and sodium picrates; Betiv., between; 

 Cane siig. and dext., cane sugar and dextrose; Carh. of Saeeli., the carbonate 

 of benzylsidphonic amide formed by the neutralization of saccharine by 

 sodium carbonate; Caud.. caudal or caudad ; Cepli.. cephalad; cl., claspers ; 

 eone.. concentration; Dors., dorsal or dorsals; flnl., finlet, caudal prolonga- 

 tion of anal and dorsal fins ; niarg., margin ; 3Ith., mouth ; Nost., nostrils ; 

 peet., pectorals; Pier. aeid. picric acid, trinitrophenol ; Quin. li.ehl. quinine 

 hydrochloride; Spir.. spiracle; Suhs., substances used as stimuli; Vent., ven- 

 tral or ventrad; ID, first dorsal fin; 2D, second dorsal fin. 



iK'ifig the only part at all iiisonsitive. At ii/40 the body surface g'Cfi- 

 crally reacts, although the reactions are less definite, particularly on 

 stimulation of ninch of the dorsal surface. At n/50 the inouth, 

 s])iracle, anus, nostrils, fins, claspers, and side are still sensitive, as 

 is also the dorsal surface beside the finlets. Stimulation of the mouth, 

 spiracle, claspers and skin beside the finlets by n/75 still calls forth 

 a reaction. At n/100 no reaction could be obtained, although the fish 

 in many cases seemed to perceive the stimulus. In all this work many 

 observations were made which indicate that the dogfish actually feels 

 stimuli to which it does not react to an appreciable extent. One 

 probably comes to a point in decreasing the concentration of the solu- 

 tions where the stimulus is perceived yet not sufficiently strong to 

 cause action of any kind on the part of the animal. All of the re- 

 actions secured at n/40 or less were weak, although usiuilly definite. 

 The reactions to acids in general are characterized by their quicktiess 



