No. 465.] ZVTERRELATIONSHIPS OF SPOROZOA. 613 
gregarine, or trophozoite. In most cases, the attachment to the 
host epithelium is sooner or later lost and the gregarine takes 
up a free life in the intestine of its host. In some species the 
attachment is maintained until the animals are sexually mature, 
but the distinction is not important. 
Although lacking in secondary sexual characters, the adult : 
gregarines are male and female. We owe this knowledge to 
the recent brilliant work of Léger. At the proper period, two 
of opposite sex come together, conjugate, and form a cyst. 
Within the cyst, the male gregarine produces motile, tailed 
elements, the spermatozoids. The female gregarine produces 
rounded cells, the eggs. At maturity, the spermatozoids seek 
and fertilize the eggs. Each fertilized egg eventually produces 
a spore, the contents of which septate into eight sporozoites. 
Ordinarily, the cysts reach the exterior shortly after their for- 
mation, and sporulation takes place while the cyst is lying on 
the earth. It may, however, be completed with the cyst still 
in the host intestine, but auto-infection has never been described. 
Eventually the cyst opens and the spores are set free. These, 
if they reach the intestine of another individual of the host 
species, dehisce and release the sporozoites. Otherwise their 
fate is doubtless death. 
In the classification given above, the Gregarinida are ranked 
as an order. This order is divided into two suborders: the 
Schizogregarine and the Eugregarine. The former includes 
those animals originally termed the Ameebosporidia. They 
possess a fixed body form, but their anatomy is much simpler 
than that of the Eugregarine. There is an alternation of gen- 
erations. So far, however, but four or five species are known, 
and this rarity appears to be actual and not merely the result of 
insufficient study. For the time being, it appears best to regard 
them merely as a small offshoot from the Eugregarinze. 
The Eugregarinz are divided into tribes. In the more recent . 
general works, these are named the Cephalina and the Acepha- 
lina. There does not seem, however, to be any good reason for 
abandoning the older terms Polycystidea and Monocystidea. 
Except for the interpolation of the Schizogregarines, this classifi- 
cation is the same as that which has been in vogue for many years. 
