204 Mr Perrin, Preliminary Communication on the Life-History 



Preliminary Communication on the Life-History of Pleisto- 

 phora periplanetae, Lutz and Splendore. By W. S. Perrin, B.A., 

 Qonville and Caius College. 



[Received 19 December 1905]. 



Pleistophora periplanetae, Lutz and Splendore, is a Myxospo- 

 ridian parasitic in the Malpighian tubules and intestine of the 

 common bakehouse cockroach Periplaneta orientalis. The spores 

 formed by this organism have apparently been seen by other 

 observers, who have, however, failed to refer them to their proper 

 genus. Thus Schaudinn* (1902) describes the presence of the 

 spores " eines Nosema " in the faeces of cockroaches examined 

 by him, and Lutz and Splendore f (1903) mention the occurrence 

 of Myxosporidian spores in the Malpighian tubules and intestine 

 of Brazilian cockroaches. These latter observers refer the spores 

 to the genus Nosema and add the species name "periplanetae." 

 The descriptions given by these authors of the spores they 

 describe, fit as far as they go the spores of the Pleistophora, which 

 is the subject of this paper, and I have therefore thought it best 

 to retain the specific name " periplanetae" while referring the 

 parasite to its proper genus. 



Methods: For examination of the living parasite the Mal- 

 pighian tubules were cut into small pieces and examined in 

 normal salt solution. 



The parasite is very inactive and the life-history has been 

 chiefly studied by the aid of stained preparations. Films were 

 made of the chopped up Malpighian tubules and either dried and 

 stained with Giemsa's modification of the B,omanowsky-Nocht 

 stain, or fixed by immersion in hot corrosive sublimate and alcohol, 

 and then stained with Heidenhain's iron-haematoxylin or Dela- 

 field's haematoxylin. The first method of staining is particularly 

 effective for differentiating nuclei from protoplasm, nuclei staining 

 red or violet and protoplasm blue. Sections were found to be 

 practically useless. Every adult Periplaneta orientalis examined 

 was found to be more or less infected, very young cockroaches 

 still possessing the yellow colour characteristic of the newly- 

 hatched cockroach alone being free from the parasite. 



Vegetative stages: The full-grown vegetative stage of the 

 parasite is an amoebiform nucleated mass of protoplasm, which will 

 be termed the trophozoite. The trophozoites vary from minute 

 specks of protoplasm 2/z — 3/x in size with one nucleus, to multinu- 

 cleated masses measuring in some cases 30yu. by 55/j, and containing 

 60 or more nuclei. 



* Schaudinn, F., Archiv. fur Protist. pp. 306 — 343. 



t Lutz and Splendore, C. B. Bakt. Pk. (1), Vol. xxxiii. pp. 150 — 157. 



