174 R. KUDO 



central portion of the spore cavity, being connected to the spore 

 membrane at one of the extremities (figs. 109, 110). The sporo- 

 plasm surrounds the polar capsule at the middle part of the spore 

 (figs. 105, 108). Unfortunately, the nucleus did not stain satis- 

 factorily. 



Thus we have here another example of a spore possessing a 

 structure similar to that of Nosema bombycis. To this group 

 may possibly belong Nosema apis (Zander, '11,- and Fantham and 

 Porter, '12), N. bombi (Fantham and Porter, '14), and N. sp. 

 (Ishiwata, '17). 



As quoted before, Leger and Hesse ('16 a) suggested that all 

 the microsporidian spores are of similar structure to those repre- 

 sented by those of Plistophora macrospora and of the genus 

 Mrazekia. In this connection, regarding the present writer's ob- 

 servation ('16) on Nosema bombycis, they wrote as follows: 

 "La, taille (of the free amoeboid mass) en est tres exigue (l^i a 

 1.5m^), alors que, dans les spores mures, qu'il dessine a la meme 

 echelle, il donne comme germe I'anneau colorable capsulaire dont 

 les dimensions sont de beaucoup superieures (comparer ses fig. 

 35 et 37, PI. I.)." It should, however, be easily understood that 

 this difference in size does not give any strong basis for interpret- 

 ing their generalization of the structure of various spores of 

 Microsporidia, if one consider the fact that there is an irregularity 

 in size among spores of Nosema bombycis as well as those of 

 other forms to a certain extent; and also that two phases of the 

 sporoplasm differ in shape, i.e., the sporoplasm assumes a ring 

 form around the polar capsule, whereas the free ameboid mass 

 outside of the spore is a solid mass. 



Up to the present, seven species of Microsporidia have been 

 reported to be parasitic in Ephemeridae. Hesse ('03) observed 

 Gurleya legeri parasitic in the adipose cell, musculature, and con- 

 nective tissue of the larva of Ephemerella ignata. The same 

 author ('05) reported later Nosema vayssierei, parasitic in the 

 adipose cell of the larva of Baetis rhodani. Lutz and Splendore 

 ('08) described briefly Nosema ephemerae a and Nosema ephe- 

 merae ^ from the intestine of the larva of an Ephemerid insect. 



2 Misprinted as '15m' 



