8 SYDNEY EVANS JOHNSON 



sheath and break up into a number of branches without anasto- 

 moses. These branches pierce the membrane in many places 

 and rise, still branching, to the bases of the sensory cells. 

 Around the bases some of the fibers intertwine in a kind of 

 basket-like network from which fibrillations rise still higher, 

 nearly to the free border of the organ, 



Heilig '12 by publishing sketches of the histology of the sense 

 organs and the terminations of the nerve fibers took an advanced 

 step. His findings in reference to endings of the nerve fibers 

 are similar to those of Bunker. Heilig's sketches are confined 

 to teleosts and chiefly to the Kaulbarsch (Acerina cernua), 

 which was the form investigated by Leydig in 1850. The 

 title of his paper is more comprehensive, embracing the lateral 

 canal organs of fishes and amphibia, and his comments on the 

 Uterature are broad and comparative. Heilig shows that the 

 nerve fibers lose their medullary sheath just below the sense 

 organ, and piercing the basilar membrane, they spread out 

 tree-like ascending between the supporting cells to the region 

 of the sensory cells. The terminal branches form a sort of 

 cup around the bases of the hair-cells (secondary sense-cells) 

 which brings the cell bodies into close relation. The upward 

 extending fibers do not reach the limiting membrane. One 

 fiber can send its terminal twigs to more than one hair cell. 

 There is no anastomosis between the terminal fibrillae. These 

 points are shown in the sketches but the difficulties of impreg- 

 nation encountered by all observers and the difficulties of ob- 

 taining good pictures of the histology leave room for clearer 

 pictures. 



Pf tiller '14 published observations on the lateral canal organs 

 and on the nervous system of the head of the Macruridae — a 

 family of deep sea fishes. Only that part of his paper that 

 deals with the lateral line organs is pertinent to the subject 

 under consideration. He shows long slender supporting cells 

 and short thick hair cells, both elements containing rounded 

 nuclei near their bases. The sense-hillocks of the head are 

 richer in sensory cells than those in the lateral canal of the 

 trunk. His histological figures are lacking in details. In his 



