VIII. THE LYMPH GLANDS IN THE GENUS P//ERE- 



TIMA WITH A NOTE ON THE COELOMIC 



ORGAN OF BEDDARD. 



By GoBiND Singh Thapar, M.Sc, Professor of Biology, 



Islamia College, Peshawar. {From the Zoological Laboratory, 



Government College, Lahore.) 



(Plate VI.) 



In the common Indian species of earthworms of the genus Pheretima 

 there occur on either side of the dorsal vessel throughout the intestinal 

 region a series of segmentally arranged whitish structures which con- 

 stitute a prominent feature in the ordinary dissection of the animal. 

 Since this genus is usually taken as a type for study in the Colleges of 

 Northern India, and since but little has been published on these organs, 

 I determined, at the suggestion of my Professor, Lieutenant-Colonel J. 

 Stephenson, to investigate them in the three common species of Phere- 

 tima which occur in Lahore, P. posthuma (L. Vaill.), P. heterochaeta 

 (Mchlsn.), and P. hawayana (Eosa). My grateful acknowledgments are 

 due to Colonel Stephenson for the help and suggestions which I received 

 from him in the course of my work. 



Beddard, whose monograph sums up what was know^i on the Oligo- 

 chaeta prior to 1895, speaks of these structures along with certain others 

 in other worms as " Coelomic Organs of problematic nature " ; "in 

 certain Perichaetidae there are a series of minute paired whitish bodies 

 lying one on either side of the dorsal vessel in the middle region of the 

 body, and springing from the septa (in P. indica), or from the dorsal 

 vessel itself (P. dyeri). These bodies are quite solid, consisting of a 

 mass of cells surrounding a few muscular fibres." P. indica is pro- 

 bably the species now known as Pheretima heterochaeta, and P. dyeri a 

 synonym for P. rodericensis. 



G.'Schneider published {Zeit. /. iviss. Zool., LXI, 1896) a paper en- 

 titled " Ueber phagocytare Organ e und Chloragogenzellen der Oligo- 

 chaten " (I have not seen his preliminary account, published in Eussian 

 with a German abstract in C. R. Sac. Natural. Petersbourg of the previous 

 year). He also investigated P. indica and P. dyeri, and in addition P. 

 barbadensis {a subspecies of P. haumjana). According to Schneider 

 . the dorsal vessel, at the place of origin of the glands in each segment, 

 lies in a sheath, which is a funnel-shaped forwardly directed diverti- 

 culum of the septum ; the glands arise from this sheath. The sheath 

 is deficient at a small opening on each side, and from the margins of this 

 opening muscular fibres branch out into the gland ; the adjoining seg- 

 ments communicate with each other through this opening. The mus- 

 cular fibres form the frame-work of the gland, which is not a solid mass, 

 as Beddard states, but a tree-like branching structure, whose twigs in 

 older examples lie so close that the whole gives the impression of a lobed 



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