CORPUSCLES OF MARINE WORMS. 145 



bodies, enclosed in a sheath of two or three cells, which 

 usually contain bright globules. The globules were shown 

 to be fat by the fact that they stained with the new fat 

 stain, Soudan III. Inside the figure-of-8-shaped body was 

 a central, dark rod, staining with haematoxylin. It seems 

 to me highly probably that the latter is some micro- 

 organism, ensheathed by the corpuscles of the worm to 

 prevent it doing harm. Metchnikoff has figured similar 

 bodies in the spleen of the Jerboa, and Jourdan in the 

 coelomic fluid of Siphono stoma. 



It is also well-known that corpuscles of Chsetopods attack 

 a parasitic nematode, and the sheath of chitin, which is 

 formed round the latter, has been shown only this year 

 by Cuenot to be formed, not by the nematode, as Metch- 

 nikoff thought, but by the leucocytes. 



This shows a wonderful power in the leucocytes 

 of producing an enormous amount of chitin at a given 

 moment. This seems to me to suggest the possibility 

 that in the worms possessing the remarkable corpuscles I 

 have mentioned, the chitinous rods represent a reserve of 

 defensive material preserved in this form till required. I 

 may mention that the same idea had suggested itself to 

 Mr. Goodrich, with whom I talked the matter over. 



Explanation of Plate IX. 

 Figs. 1 — 4. Notomastus profundus, Hsemolymph. 



Fig. 1. Fusiform corpuscle, possibly an early stage of 

 the bow-cell. A rod-like structure is seen within 

 it. Fresh, X 480. 



Fig. 2. Hsemolymph, showing ordinary cells and three 

 bow-cells. The nuclei are stained. From a 

 photograph, kindly taken by Dr. Gustav Mann. 



