CLASSIFICATION 



737 



that the infective agent, containing one or two nuclei, lies behind the polar 

 capsule in the clear space at the posterior part of the spore. The envelope 

 of the spore consists, in some cases at least, of two valves. The develop- 

 ment of the spore from the single cell (sporoblast) which gives rise to it 

 appears to be a very complicated one. A number of cells are formed, as 

 in the development of the spores of Myxosporidiida, and some of these 

 give rise to the outer covering of the 

 spore; others form the polar capsule and 

 infective amoeboid bodv. 



Subdivision of the Microsporidiida. 



Doflein (1901) classified the Micro- 

 sporidiida on the basis of the number of 

 spores produced by each pansporoblast, 

 but Leger and Hesse (1922a) point out 

 that many forms are far from constant in 

 the number of spores produced, a fact 

 previously noted by Chatton and Krempf 

 (1911). It is maintained that the only 

 constant feature on which a classification 

 can be based is the character of the spore 

 itself, and, as in Kudo's classification of 

 the Myxosporidiida, they propose a system 

 which has the character of the spore as 

 its basis. They divide the Microsporidiida 

 into two groups — the Monocnidea, which 

 have spores with one polar capsule; and 

 the Dicnidea, with spores with two polar 

 capsules. The former appear to be of two ^ 

 types. In the one the parasite is a multi- 

 nucleate cytoplasmic body, which is con- 

 stantly increasing in size, and when de- 

 veloping often includes the nuclei of tissue cells 

 certain uninucleated cells (pansporoblasts or sporonts) become separated in 

 vacuoles in the parent cytoplasm, and these give rise to spores (Fig. 304, D). 

 Parasitesof this type are called Polysporogenea (family Glugeidse) by Doflein 

 to distinguish them from those of the second type, Oligosporogenea (family 

 Nosematidae), which in the vegetative stage are uninucleate bodies multi- 

 plying by binary fission or schizogony. Finally, as in the Polysporo- 

 genea, pansporoblasts are formed, and these give rise to a varying number 

 of spores (one to sixfeen or more). It must be admitted, however, that 



I. 47 



Fig. 31.3. — Structure of Micro- 

 spoRiDiAN Spores. (1 and 2, 

 AFTER Kudo, 1920; 3, after 

 Leger and Hesse. 1916.) 



1-2. ^Tpore oi Stempellia magna (x 2,360). 



1. Extruded filament, polar capsule, 



and infective body- 



2. Same before extrusion of filament. 



3. Spore of Plisto'phora Diacrospora 



(x 2,500). Polar capsule with 

 coiled filament and infective 

 body with two nuclei. 



As in the Myxosporidiida, 



