120 SMELL, TASTE, ALLIED SENSES 



by Graberg (1899) extrabulbar cells and though they are 

 not to be classed as part of the bulb proper they are 

 nevertheless sufficiently related to that structure to be 

 appropriately mentioned in this connection. 



As Hermann (1889) long ago pointed out, the cells of 

 the taste-buds are probably undergoing continual change. 

 Old cells are degenerating and disappearing and new 

 ones are forming to take the places of those that have 

 broken down. The degenerating process is indicated by 

 the presence in the taste-buds of cells in all stages of 

 growth and of considerable numbers of leucocytes, as 

 pointed out by Ranvier (1888), von Lenhossek (1893b), 

 and others. The regenerative process is shown in the 

 occasional occurrence of mitotic figures in the base of 

 the bud thus giving evidence of cell division in that region 

 Hermann (1889). 



5. Intragemmal and other Spaces. Graberg (1899) 

 has called attention to the fact that taste-buds are not 

 solid structures but that their cells are separated one from 

 another by considerable intervening space, and that 

 much free space occurs in the tissue immediately around 

 the buds. This intra-, peri-, and subgemmal space is be- 

 lieved by Graberg not to be an artifact, for it can be 

 identified by almost all methods of preparation. Accord- 

 ing to this investigator these various spaces communicate 

 with one another and connect with the exterior through 

 the taste pore. They may be the means of irrigating and 

 thereby cleaning the taste-bud, for it is possible that 

 fluid may flow slowly through them from the interior to 

 the exterior. 



6. Innervation of Taste-buds. Among the older in- 

 vestigators the innervation of the taste-buds was a ques- 



