142 THOMPSON YATES AND JOHNSTON LABORATORIES REPORT 
various degrees inside the capsule, the length varies from 75 to 84-7 /u. The nuclei 
of very small cells are evident, but indications of V or other shaped spots are very 
indefinite and irregular.' 
Yonng Filariae in the Bird Lice. — The following table shows the number of lice 
taken from the infected birds examined and the number found infected : — 
Date 
Number of lice examined 
No. of lice containing 
filariae 
Nov. 1 
5 taken from 3 infected birds 
3 
Dec. 2 
6 „ 1 ,, bird 
0 
6 „ „ 1 
The lice were dissected in normal saline solution on a slide ; as a rule the head 
and mouth parts, the thorax, and the abdomen were examined separately. In the 
two former portions filariae were never seen. The intestinal canal of the first 
louse found infected was drawn out in a manner similar to the method by which 
the ' stomach ' of the mosquito is obtained for examination. On examination of the 
preparation under the microscope large and small filaria were seen free in the saline 
solution. In all of the first three infected lice, variously sized free filariae were found 
in their abdominal cavities. 
On December 2, as seen from the table, six lice obtained from one infected bird 
showed no filaria, at least none were found in the abdominal cavity. After this 
batch was examined, a more minute dissection was made of the walls of the abdomen 
in the lice taken from the other infected bird, and was rewarded by the discovery of 
very young forms of filariae in the loose tissue lying beneath the chitinous exoskeleton. 
The tissue containing these young forms is probably the fat body, as no muscular 
structure was observed in it. 1 No filariae were seen in the malpighian tubules or in 
the stomach wall. Altogether over twenty filariae were observed in all stages of 
development in the fat body and free in the abdominal cavity. In the latter 
situation very long and active forms were seen, resembling in miniature the parent 
worms found in the subcutaneous tissue of infected swifts. 
From the above material the steps in the metamorphosis of the parasite in the 
louse can be almost completely worked out. For convenience the following stages 
will be described : — 
Stage I (Fig. 2). — The embryo loses its sheath and its body becomes slightly 
granular ; there is no alteration in length or shape of the worm. The loss of the 
sheath probably takes place in the stomach of the louse, as small embryos, both with 
1. Grassi has observed various stages of the metamorphosis of F. reconduct in the fat cells of Pulex serraticeps, P. irritans > 
Rhipicephalm siculus (Koch). 
