156 
E. A. MINCH IN AND H. M. WOODCOCK. 
20th — just a month. Leucocytozoon was very scarce in 
this bird. It was not found in the living examination on 
April 20th ; but on April 23rd a single individual was noticed 
in two cover-slip preparations. Examined again on May 9th 
(morning) and also on May 12th-13th (midnight) no Leuco- 
cytozoa could be seen in the living drops. But a very 
few individuals have since been found on searching permanent 
smears made on these occasions. Hence the parasites were 
present in the general circulation, though so scanty that their 
presence could not be demonstrated in the routine examina- 
tion of several living drops on both occasions. Further, in 
the smears made from the heart-blood of the dead'bird on 
May 20th Leucocytozoon is also present, though very 
scanty. 
From the above observations we think, therefore, it is 
practically certain that in none of our owls infected with 
Leucocytozoon was this parasite at any time really absent 
from the general circulation. 
The variation in number and ripeness of the gametocytes, 
and their occurrence at times in distinct batches, is most 
probably the result of some antecedent process of schizogony, 
by which the sexual forms have originated. A schizogonic 
mode of multiplication has been briefly described by Fantham 
( 4 ) in L. lovati of the grouse; and a similar phase occurs 
in all likelihood in other Leucoc 3 ’tozoa. At a particular 
moment, we may suppose, a number of young (potential) 
gametocytes are liberated by the breakdown of the host-cell 
in some internal organ in which they have been developed. 
They penetrate, probably as soon as possible, into the new 
leucocytic host-cells in which they will grow and mature, and 
so pass into the blood-current, in which they are passively 
borne along. As it is quite probable that different host-cells 
(or groups of host-cells) containing the products of schizogony 
become ruptured at different times, we should have, in that 
case, clumps or batches of gametocytes of slightly different 
age and ripeness in different small quantities or volumes of 
blood. 
