MICROSPORIDIA 331 



tively easily. As in the case of myxosporidia, various reagents 

 have been proved as capable of causing- the filament-extrusion from 

 fresh microsporidian spores (see Kudo, 1924, pp. 22 and 58). It 

 seems, however, that one reagent may be efficient in bringing about 

 the filament-extrusion in certain species, while it may fail com- 

 pletely in other species, which reason remains undetermined. 

 Schwarz (1929) used a concentrated watery solution of methylene- 

 blue for vital staining with two per cent acetic acid, and Zwolfer 

 (1926) successfully used methylene-blue (1:1000) and neutral 

 red (i: 100). Georgevitch (1929) succeeded in causing the fila- 

 ment-extrusion by Schulze's solution which had been used pre- 

 viously by Zwolfer (1926) for staining extruded polar filaments. 

 Although considered to be too violent and consequently the extru- 

 sion to be unnatural, the mechanical pressure method is preferable 

 to other methods in many cases when the material is too scanty to 

 test out which reagent would be effective, since it brings out with- 

 out failure the filament of the microsporidian spore. 



Although the extruded polar filaments are noticeable without 

 staining with an ordinary microscope, the darkfield microscope will 

 greatly facilitate their detection. To make permanent preparations, 

 use Loffler's, Fontana's, Giemsa's or Schulze's solution. Addition 

 and spreading of a drop of ink or nigrosin and mounting in Canada 

 balsam when dry, makes excellent preparations (Alorgenthaler). 



Besides the spore, the schizonts and sporonts at various stages of 

 development may be noted in the fresh hanging-drop preparation. 

 The sporonts are more or less easily noticed especially in poly- 

 sporoblastic species, since the developing spores are grouped in 

 characteristic manners. These should be studied and measured. 

 The schizonts are not very readily recognized in the fresh condi- 

 tion, because of the smaller size as well as of lack of distinct 

 characteristics. 



The presence of the polar filament in the spores suffices one to 

 hold definitely that the spores are those of a microsporidian. Aside 

 from a single genus in which each spore possesses two polar fila- 

 ments, all the other species of microsporidia possess spores with 

 a single filament only. To which family the microsporidian belongs, 

 can be determined by'the general form of the spore. In some cases, 

 the generic determination may be possible in the fresh condition. 

 For example, if one sees numerous octosporoblastic or octosporous 

 sporonts together with ovoid or pyriform spores, one is fairly cer- 



