MICROSPORIDIA 333 



difference in structure of spores of various forms studied by the 

 same investigator using the same methods would lead one to think 

 that different microsporidian spores are not similarly constructed. 

 Without taking this point into account, investigators have at- 

 tempted to interpret the structure of microsporidian spores studied 

 by other observers on the basis of their own observations, which 

 has resulted in a confused state of our knowledge, as indicated in 

 the following summary of opinions regarding the subject: 



a) A definite polar capsule is present in the spore. 



(i) The sporoplasm is girdle-like (ring in cross-section) which 

 surrounds the polar capsule at the middle portion of the spore. 

 Thelohan was the first one to attempt to interpret the structure 

 of a microsporidian spore. He made out, by heating the spores with 

 nitric acid, a pyriform polar capsule which was surrounded by a 

 coat of protoplasm. Mercier (1908) observed that in a mature 

 spore of Thelohanio giardi, there is a pyriform polar capsule with 

 a coiled polar filament, which occupies about two-thirds of the 

 iritrasporal cavity and attaches itself to the narrow end of the 

 spore. The sporoplasm presents a girdle-like form at the central 

 part of the spore, through which the capsule penetrates. Stempell, 

 Schroder, Kudo, Schwarz (1929) and others, agreed on the whole 

 with Mercier. Some authors, for instance Fantham and Porter, 

 considered the vacuole near the anterior end as the polar capsule. 



(2) The sporoplasm is located near the posterior end and the 

 polar capsule in the anterior portion of the spore. Leger and Hesse 

 (1907) considered that in the spore of Nosema bombycis there 

 was a comparatively large polar capsule near one end and the 

 sporoplasm was located close to the opposite end. These authors 

 found later a similar structure in Plistopliora macrospora 

 (1916a). Similar structure was observed in the spores of Plis- 

 topliora elcgans (Auerbach), Thclohania acuta (Schroder), 

 T. varians (Debaisieux), Plistopliora (Glugca) danilcwski (Guye- 

 not and Naville), Nosema apis, N. cyclopis, N. anophelis, Thelo- 

 hania obesa, Stempellia magna (Kudo), Thelohania vandeli (Pois- 

 son, 1924), Nosema nepce (Poisson, 1928), etc. 



b) There is no polar capsule; the polar filament occurs exposed 

 to the intrasporal cavity. 



(i) The polar filament occupies one end, while the sporoplasm 

 the other. Leger and Hesse (1916) found that in the spores of 

 Mrazckia, which are cylindrical in form, the polar filament which 



