PARASITES OF SIMULIUM LARVAE 5) 
triculus and must remain open at the end all the time the food 
is carrying it backward through the mesenteron. This would 
give the young germ, liberated from the spore by the action of 
the digestive juices, ample time to escape from the open end 
and thus get into actual contact with the epithelium, from which, 
soon after, it would be entirely cut off during the remainder of 
the larval life. 
CLASSIFICATION OF THE SPOROZOA 
The class Sporozoa consists of essentially parasitic Protozoa, 
from the attacks of which, in all probability, none of the higher 
forms of life from the annelids up to the vertebrates is immune. 
The most salient characters of the class are the following: 
1. Nutriment is always of a fluid nature and is absorbed by 
osmosis. 
2. Ingesting and digesting organs are never present. 
3. Flagella may be present in certain stages of development; 
these are used for locomotion or attachment but never for 
nutrition. 
4, Certain stages may be amoeboid, but the pseudopodia are 
‘used exclusively for locomotion. 
5. All forms are capable of sporulation in order to increase 
the infected area of their host, or by the spores escaping from 
it to spread the disease. 
The Sporozoa are divided by Schaudin into two subclasses as 
follows: 
Subclass I: Telosporidia. Sporozoa in which spore formation 
ends the individual life; the entire cell then forms spores. Thus 
the reproductive phase is distinct from ahd follows the trophic 
phase. To this subclass belong three orders: Gregarinida, Coc- 
cidiida, and Haemosporidia. I shall have occasion to refer to 
the first of these three orders, namely, the Gregarinida, later. 
Subclass II: Neosporidia. Sporozoa in which reproduction 
begins during the trophic phase and the entire cell is not at once 
used up in the production of spores. To this subclass belong 
two orders: Myxosporidia and Sarcosporidia. 
The Myxospiridia, with which we are mainly concerned in 
this paper, have the following characters: 
