56 E. H. STRICKLAND 
1. The earliest stage of the trophozoite is amoeboid. 
2. Spore formation usually begins at an early period and con- 
tinues during the growth of the trophozoite. 
3. The spores are produced endogenously. 
4. Each spore possess one or more polar capsules. 
There are two suborders of the Myxosporidia, mainly separable 
on spore characters. These are: 
Suborder I Phaenocystes (Gurley) = Myxosporidia sens. sér., 
with large bilaterally symmetrical spores having two or four polar 
capsules which are plainly visible in the fresh state. Two spores 
are formed in each pansporoblast. 
Suborder II Cryptocystes (Gurley) = Mlicrosporidia (Bal- 
biani), with minute pyriform or oval spores having one polar 
capsule, which is visible only after treatment with reagents such 
as weak HNOs, and in some cases not even then. One (Nosema), 
or more than two spores are formed in each pansporoblast. 
The Protozoan parasites of Simulium larvae all (with the 
exception of an undetermined Gregarine) fall into the second of 
these sub-orders, namely the Microsporidia of Balbiani. 
TYPICAL LIFE CYCLE OF A MICROSPORIDIAN 
The Microsporidian genera are distinguished entirely by their 
mode of development, and largely by the final stage, i.e., sporu- 
lation. <A brief account of the development and means of infec- 
tion of these parasites will be useful before we pass to the generic 
classification. 
Stage I: The germ. ‘This name is applied to the minute amoe- 
boid, motile body which is liberated in the alimentary canal of 
its host from a spore which has been taken in with food. At the 
time of liberation the germ has either one or two nuclei. In the 
latter case the two nuclei soon fuse. A minute vacuole is also 
sometimes present (Stempell 09). The germ passes between the 
epithelial cells of the gut and so reaches the blood sinuses. It 
is now termed a ‘planont.’ 
Stage II: The planont. This body is also minute and neither 
this nor the preceding stage have been actually found in the 
great majority of described Microsporidia. The best account is 
