2 20 LANGDON. [Vol. XI. 



gland-cells. The network from the bases of the supporting 

 cells was also probably bits of these nerve-fibres apparently- 

 continuous with the true basal processes of these cells. Ley- 

 dig's figures of these cells show that they are supporting cells, 

 and precludes the possibility of referring this to the true sense- 

 cells. The basal processes of the supporting cells are under- 

 stood when one remembers the layer of basal cells beneath 

 them. Ude ('86) and Cerfontaine ('90) are the only ones who 

 refer to these basal cells. There is no connection of nerve- 

 fibres with the bases of either gland or supporting cells. 



Sense-organs. — Leydig ('65), the discoverer of the sense- 

 organs, saw them as " blase rundliche Flecken," which appeared 

 by focusing below the surface. He described these spots as five 

 or six times larger than the surrounding cells, and often lim- 

 ited by pigment. Of their minute structure he could only see 

 that each was formed by a certain grouping of cells. I have 

 found only the sense-organs of the dorsal surface of the head 

 end limited by pigment. This may be of physiological inter- 

 est. Perrier ('73) recorded his inability to find any sense-organs 

 in Lumbricus, but he made only surface examination. Mojsi- 

 sovics ('77) was the first to describe the sense-organs as seen 

 in sections, and to figure their cellular structure. His figures 

 do not show the true form of the sense-cells. He represented 

 these cells as differing from the supporting cells merely in the 

 possession of terminal hairs. He gave F. E. Schulze credit for 

 discovery of the " Porencanalchen," through which the sense- 

 hairs pass, but he himself seems to have first seen the corre- 

 sponding cuticular markings in surface view. Darwin ('82) 

 referred to Lumbricus as " remarkably deficient in the several 

 sense-organs." Vejdovsky ('84) and Ude ('86) verified Mojsi- 

 sovics' description of the sense-organs and their cuticular 

 markings, but Ude failed to find the sense-hairs. It seems 

 to me probable that in his preparations these hairs were drawn 

 into the pore canals. Vogt and Jung ('88) were not only un- 

 able to find any sense-organs themselves, but stated that such 

 organs are unknown. Kulagin ('90) found the " Zellenanhauf- 

 ungen " described by Ude. He probably refers to the sense- 

 organs. Cerfontaine ('90), although he gave a more complete 



