160 Miscellaneous. 



original structure. Ilerr Henuings has shown tliat the thickness of 

 the inside wall of these structures consists of sensitive epithelial 

 cells, the nuclei of which are found in the proximal parts, while the 

 more superficial layers contain some small granules in the proto- 

 plasm of the cells. Herr Hennings rightly considers the cells of 

 this wall of the organs to have a nervous function ; those which he 

 represents in his figure 2, and which he calls cells of the sensitive 

 epithelium, are glandular ceDs. The structure of the internal wall 

 in question of the lateral organ is considerably complicated. 



The wall consists of very abundant glandular cells, which com- 

 municate by means of very narrow canals with the bottom of the 

 cavity of the organ ; on the chitinous surface of the bottom minute 

 pores even may bo made out through which the secretion of the 

 cells enters the cavity of the organ. 



Besides the glandular cells there are to bo seen in the still more 

 proximal layers not far from the cells of the adipose tissue large 

 ganglionic cells, which are prolonged at their proximal ends into 

 the nerves which spring from the main nerve of the organ, while at 

 their distal extremities they are drawn out into long terminal 

 nervous filaments ; these filaments, which can be well seen when 

 examined by llamon y Cajal's method, reach the chitinous layer 

 and sometimes raise it, forming little cushions. If a section is made 

 parallel to the surface of the cavity, it can be distinctly seen that 

 each terminal filament, which has here a structure recalling the 

 rhabdomeres in the sense-organs of Arthropoda, is surrounded by 

 the canals of glandular cells. The latter form polygonal figures 

 recalling the meshes in tulle net, and in the centre of the meshes 

 a nervous filament ends. 



Between the canals of glandular cells very abundant concretions 

 are found ; these stain with all the colouring reagents and remain 

 after boiling in caustic potash. 



The combination of glandular and sense-cells and their structure 

 strongly recall olfactory organs, and I think that one ought to attri- 

 bute such a function to the organs in question. 



The structure as well as the evident function of the lateral 

 cephalic organs of GJomeris approach those of the cephalic organs of 

 segmented worms. If we remember that Peripatus retains traces 

 in its adult stage of the cephalic organs well developed in the embryos 

 and young examples, and that several other arthropods present in 

 their development traces of remarkable cephalic organs, if we recol- 

 lect, again, that the relationship between the segmented worms and 

 the arthropods through the link furnished by Peripatus becomes 

 more and more evident, we can evolve the hypothesis that the lateral 

 cephalic organs of GJomeris are homologous with, and even perhaps 

 analogous to, the cephalic organs of annelids. — Comptes Rendus, 

 t. cxxix. (1899) pp. 504-506. 



