155 



Observations on the Life-history of Adelea ovata, Aime Schneider, 

 ivith a Note on a New Gregarine from the Gut of Lithobius 

 forficatus. 



By C. C. Dobell, B.A, Scholar of Trinity College, Cambridge. 



(Communicated by J. J. Lister, F.E.S. Keceived November 19, 1906, — 

 Eead January 17, 1907.) 



[Plates 2 and 3.] 



At the suggestion of Mr. J. J. Lister, F.K.S., I recently undertook a 

 reinvestigation of the sporozoan parasites occurring in the gut of the 

 centipede, Lithobius forficatus. The present paper is the result of these 

 investigations. It is with pleasure that I take this opportunity of expressing 

 my thanks for the advice and assistance I have received not only from 

 Mr. Lister, but also from Mr. Adam Sedgwick, F.E.S., and from Mr. W. S. 

 Perrin. 



No less than six protozoan parasites have been recorded from the gut of 

 Lithobius forficatus — four Coccidia and two Gregarines. The Cambridge 

 centipede appears to harbour but a single one of the former — namely, 

 Adelea ovata, A. Schn. — whilst both the latter* have been observed in rather 

 less than 1 per cent, of the animals examined. It is with the sexual phases 

 of the life cycle of A. ovata that the present paper is chiefly concerned. 



Previous Wokk. — Adelea ovata was first described^ by Aime Schneider 

 in 1875 [12], and although a part of the sexual process was observed, it was 

 not recognised as such. Schneider published some further particulars 

 in 1892 [14]. In 1897 Schaudinn and Siedleckiif published a preliminary 

 account of the Coccidia of the centipede, and later — in 1899 — Siedlecki [16] 

 gave a detailed description of the whole life-history of Adelea ovata. 

 Subsequent writers have described other species of the genus Adelea, and in 

 all cases the life cycle appears to correspond closely with that recorded 

 by Siedlecki. I may say that I am able to confirm most of the results 

 obtained by this writer, but I have come to different conclusions regarding 

 one or two points. The most important of these deals with the formation of 

 the microgametes. 



Methods. — The best results have been obtained by adopting Schaudinn's 

 methods [11]. The entire gut was removed, and the epithelial cells and gut- 

 CQntents spread out upon a coverslip. The films thus obtained were 



* Viz., Actinocephalus dujardini, A. Schn., and Echinomera hispida, A. Sehn. 



t As a gregarine. 



X Schaudinn and Siedlecki, ' Sitz. ber. d. d. zool. Gesell.,' 1897. 



