86 Bulletin of Laboratories of Denison University. [Voi. xii 



CONCLUSION. 



The morphological and physiological significance of the 

 terminal buds of fishes is a problem which has exercised some 

 of the ablest morphologists for over half a century. The methods 

 of the older anatomy have signally failed to yield concordant re- 

 sults. Not until the innervation of the cutaneous sense organs 

 was worked out from the standpoint of nerve components was 

 their confusion relieved. The older morphologists (Schulze, Mer- 

 kel and others) discovered a morphological criterion, the "hair 

 cells," by which the terminal buds could be distinguished from 

 cutaneous sense organs belonging to the lateral line system. 

 But this fact attained its significance only when it was discov- 

 ered that the organs of the lateral line system, or neuromasts, 

 which possess the "hair cells" are always innervated by lateralis 

 nerves related centrally to the tuberculum acusticum, while 

 terminal buds, which lack the "hair cells," are always innerva- 

 ted by communis nerves which are related centrally to the pri- 

 mary gustatory centers of the vagal and facial lobes. 



Presumably, then, lateral line organs and terminal buds 

 have different functions, and further the function is probably not 

 tactile in either case, since all parts of the skin receive general 

 cutaneous nerves in addition to the special sensory components 

 and these general cutaneous nerves are related proximally to 

 different centers from either of the others. The lateral line or- 

 gans are known to be used in the maintenance of bodily equi- 

 librium and the perception of mass motion of the water (com- 

 pare the recent works of Lee and Parker). On the other hand, 

 the terminal buds are related in structure and innervation to un- 

 doubted taste buds of the mouth and hence the inference that 

 their function is taste. This inference is abundantly confirmed 

 by the experiments here recorded; and the function and 

 morphological rank of the terminal buds are at last definitely 

 fixed. 



It may be regarded as established that fishes which possess 

 terminal buds in the outer skin taste by means of these organs 

 and habitually find their food by their means, while fishes 



