22 THE GUSTATORY ORGANS, BY TH. W. ENGELMANN. 



The second kind of cell, which corresponds to the gustatory 

 cells of other Mammals, are most numerous in the central 

 parts of the cup. These are very long slender cells, that con- 

 sist of a small elongated elliptic body, with two thread-like 

 processes. The body of each cell is almost entirely filled by a 

 nucleus which contains distinct nucleoli in its interior. The 

 peripheric process is far longer than the centric, but, like it, is 

 an extremely delicate straight and cylindrical thread. The 

 central process is frequently (after the action of a 0' 5 to 1 per 

 cent, solution of bichromate of potash) very regularly varicose. 

 This is sometimes also seen in the peripheric process. 



The connection of these cells with the nerve fibres that 

 ascend in the papilla to the base of the gustatory cups, has 

 not as yet been observed. 



Future investigation must determine whether amongst the 

 numerous sensory apparatus that are imbedded in the skin of 

 many invertebrate animals, and which have commonly been 

 regarded as tactile organs, some must be regarded as gustatory 

 organs. 



No details are known in regard to the development of the 

 gustatory organs.* 



METHODS OF RESEARCH. 



For the investigation of the gustatory organs of Mammals, the 

 lateral gustatory organs of the Rabbit and Hare may be recommended 

 as appropriate for rapid demonstration. The knowledge of the 

 coarser anatomical features, as the position, arrangement, number, 

 size, etc., of the bulbs is acquired, as in the case of the gustatory papilla, 

 by dried preparations, and by the examination of sections which have 

 been macerated in dilute acetic acid and glycerine. Or the specimen 

 may be hardened for about twenty-four hours in perosmic acid, 

 containing 0'5 1/5 per cent. ; sections being then made which can be 

 rendered transparent by glycerine. The freezing method can also be 



* Supplementary note. F. E. Schulze has very recently discovered cup- 

 sliaped organs in the papillae of the oral cavity of the Tadpole, closely 

 agreeing in their structure with those of the Fish. Perhaps these are the 

 early stage of development of the gustatory disks. 



