228 SMELL, TASTE, AND CHEMICAL SENSE IN VERTEBRATES. 



so brief that it could contain only an incomplete statement of results. The first 

 exhaustive piece of work on the chemical sense in vertebrates was that by Sheldon 



(1909) 



the dogfish 



Sheldon's results are expressed in terms that admit 



easy comparison with my work and are included in part in the following table 

 which embraces observations on Amphioxus, Ammoccetes, and Amiurus from my 

 own investigations, on Mustelus from Sheldon's work, and on man from several 

 sources all of which, however, have been checked by me. The table shows for 

 the three parts of the body of each of the five animals tested the weakest solution 

 of a given substance that, so far as is known, will call forth a response. 



TABLE ill. 



Bitter, and Sweet Substances 





Table of Minimum Concentrations of Acid, Alkaline, bALT, 



that Will Call Forth Responses from the Mouth, Mid-trunk, and Tail Regions 



of Certain Vertebrates. 



The records for Amphioxus, Ammocoetes, and Amiurus are based on observations by me (Parker, 

 1908\ 1912) ; those for Mustelus on observations by Sheldon (1909) ; and those for man on observations 

 by several workers, checked by me. The concentrations of the acid, alkali, and salt solutions are 

 expressed in terms of a normal solution; those of the quinine and sugar solutions in terms of a molecular 

 solution. N.R. indicates that even to a concentrated solution no reaction was given. 



Regions of Body. 



1 Animals. 



HCl. 1 



NaOH. 



NaCl. 1 



Quinine. 



Sugar. 



Mouth. 



A mphioxus 



Ammoccetes 



Mustelus 



Amiurus 



Man 



n/500 



n/1,280 

 n/75 

 n/20 

 n/1,000 



n/10 

 n/20 

 n/50 



n/2 



n/100 



n/40 



n/40 



n/2 



n/1,000 

 n/10 

 n/100 

 n/400 



n/100 



n/20 



n/40 



n/500 



n/20 



n/40 



n/40 



n/50 

 n/50 



m/640 



ro/150 

 m'/25,000 



n/10 



N.R. 



N.R. 



m/20 

 N.R. 

 N.R. 



N.R. 

 N.R. 

 N.R. 



N.R. 



m/50 



Mid-trunk. 

 Tail. 



Amphioxus 

 A mmocoetes 

 Mustelus 

 Amiurus 



A mphioxus 

 Ammoccetes 

 Mustelus 

 A miurus 



2n 

 2n 



n 

 2n 



N.R. 

 N.R. 

 N.R. 

 N.R. 



N.R. 

 N.R. 

 N.R. 

 N.R. 



I 



A detailed inspection of Table III shows several significant features. None 

 of the three fishes tested by me showed any response from any part of their 

 bodies to sugar solutions even when of high concentration (2m) , and in 

 respect my results agree with those of Sheldon (1909) on the dogfish. Ine 

 statement made by Nagel (1894, p. 184) that a sugar solution will stimulate the 

 mouth region of certain fresh-water fishes is put in so vague and uncertain a waj 

 that I am inclined to regard it with question and to agree with Sheldon ( 

 p. 288) in believing that most fishes will be found to be unstimulated by sap 

 solutions. This condition has probably resulted from the fact that sugar is 

 unusual material in the environment of fishes. From this standpoint the poss^ 

 sion of gustatory organs capable of being stimulated by sugar, as in man ^ gi- 

 other air-inhabiting vertebrates, may be regarded as a relatively recent acq 

 tion and probably associated with the production and storage of sugar in 

 restrial vegetation. . 



