48 D. KEILIN 
tissue is blue (PI. 8, figs. 7 and 8). Some of the sections of 
All. foetida stained by the latter method showed the 
actual discharge of the mucin from the terminal or dis- 
charge pockets (d. p.) ito the pharyngeal lumen (Pl. 3, 
fic. 8 d. p. and mu.). The latter in all sections is shown to 
be filled with mucin (mu.), which flows partly towards the buccal 
cavity and partly towards the oesophagus. It is very 
important to examine now a number of observations of 
certain histologists, who, treating of the minute structure 
of this organ from quite a different standpoimt, and 
using a totally different technique, discovered nevertheless the 
ductules with their discharge pockets in the pharyngeal 
epithelium, but unfortunately completely misunderstood their 
nature and their function. I am alluding here to the papers 
dealing with the study of the peripheral nerve endings and 
sensory cells of earthworms. 
In 1892 Retzius discovered in the pharyngeal epithelium 
special fibrils which he named clubbed fibrils—‘ Kolbenformige 
fasern’—and which he supposed to be the gustatory sensory cells. 
In 1894 Smirnow, to whom we owe the discovery of free nerve 
endings in the skin and the pharyngeal epithelium of the earth- 
worm, using Golgi’s method, detected in the pharyngeal 
epithelium the clubbed cells of Retzius.* 
Smirnow’s description of these cells closely resembles that of 
Retzius ; he found in the pharyngeal epithelium an enormous 
number of these cells, which in their terminal dilated portion 
seem to contain nuclei. Their elongated portion he described 
as somewhat tubular with the lumen filled with a granular 
substance, and the whole structure of the club-shaped cells 
leaves, according to Smirnow, some doubt as to their nervous 
origin. 
A year later (1895) Retzius confirmed Smirmow’s discovery 
of the free nerve endings of the skin and the pharyngeal 
epithelium of the earthworm ; and, returring to the subject 
of his clubbed fibrils, he now denied the existence of nuclei inthe 
1 Tt may be mentioned that, under the name of oesophagus, Smirnow was 
actually dealing with the salivary portion of the pharynx. 
