254 
PACIFIC SCIENCE, VoL V, July, 1951 
TABLE 2 
Incidence of Tetrameres sp. in Individual Glands of Proventriculus of Infected Sparrows 
.BIRD 
NO. 
glands 
INVADED 
NO. 
ADULT 
NO. 
cf PER GLAND 
NO. cf IN 
PROVENTRICULAR 
LUMEN 
9 
d’ 
Min. 
Max. 
Mean 
1. 
1 
1 
4 
— 
— 
4.0 
0 
2. 
10 
10 
18 
0 
4 
1.8 
8 
3. 
1 
1 
2 
- 
- 
2.0 
0 
4. 
1 
1 
2 
- 
- 
2.0 
0 
5. 
1 
1 
1 
- 
- 
1.0 
0 
6. 
2 
2 
1 
0 
1 
0.5 
3 
7. 
2 
2 
4 
0 
4 
2.0 
0 
8. 
1 
1 
0 
- 
- 
0.0 
1 
9. 
1 
1 
1 
- 
- 
1.0 
2 
10. 
1 
1 
4 
- 
- 
4.0 
0 
11. 
3 
3 
1 
0 
1 
0.3 
0 
12. 
3 
3 
3 
0 
2 
1.0 
0 
13. 
2 
2 
3 
1 
3 
1.5 
1 
14. 
2 
2 
1 
0 
1 
0.5 
2 
15. 
1 
1 
3 
- 
- 
3.0 
0 
16. 
1 
1 
1 
- 
- 
1.0 
2 
17. 
2 
2 
3 
0 
3 
1.5 
0 
Totals . . 
35 
35 
52 
0 
4 
1.4 
19 
mature. Table 1 also presents some data on 
the number of proventricular glands invaded 
in the parasitized birds, the average number 
of invaded glands per bird being 2.1. 
Individual parasitized proventricular glands 
were examined and it was found that no more 
than one female nematode per gland was the 
rule. The number of males varied from zero to 
four, with an average of about 1.4 per gland 
for all glands examined. Additional male 
worms were found in the proventricular 
lumen (Table 2). It should be noted that, un- 
like other Tetrameres species heretofore 
studied, the present form eventually reaches 
the outside stomach wall subsequent to its 
invasion of the gland from within the lumen. 
When a sparrow is first dissected, these 
globular, bright red female worms can be 
seen surrounded by the delicate intima of the 
outer stomach wall. They exert considerable 
pressure on this membrane, for a slight cut 
with a scalpel results in immediate expulsion 
of the female (see Fig. 1). 
The mature female is nothing more than a 
sac of uterine coils filled with eggs, many of 
which are embryonated. These embryonated 
eggs have polar filaments about 12^^ in length, 
and the eggs themselves are about 52/x long 
by 30 )U wide (Table 3). 
Although the grasshoppers used here may^ 
not be the actual intermediate hosts in 
nature, the sparrow Tetrameres completed de- 
velopment in them. The parasite underwent 
two molts in these hosts — from the first to 
second, and second to third larval stages. The 
third larval stage was typically filariform and 
is presumed to be the infective stage for the 
vertebrate host. These third stage larvae were 
TABLE 3 
Measurements in Microns of 25 Embryonated 
Eggs of Tetrameres sp. Taken From Female Uteri 
SIZE 
MIN. 
MAX. 
MEAN 
Length 
50 
55 
52.2 
Width 
29 
33 
30.4 
Length of polar filament 
9 
15 
12.0 
