334 
NABORE, 
[Aucust 3, 1899 
In every mosquito examined, with one exception, the coccidia 
were found usually in numbers, but in one there was only one 
coccidia. 
The exception occurred on the ninth day ; as by then they had 
been re-fed several times, it may have been an outside one which 
had effected an entrance. 
So that out of forty-five mosquitoes fed on the infected birds 
and examined more than thirty-four hours after, forty-four 
contained coccidia, : 
This I may say is a more successful result than in the other 
series I have seen. 
The other two sets of mosquitoes were used by all of us for 
preparation of specimens, and no record was kept of the number 
of failures. From my own examination only about three- 
fourths of them developed coccidia. 
The treatment was a little different, and half of them were not 
incubated for several days. 
OF the controls fed on birds free from proteosoma, thirty- 
eight in number and treated in the same manner, twenty-nine 
were examined and nine are unaccounted for—‘* lost in the nets.” 
None of the twenty-nine were examined on the first day, but 
one was in the afternoon of the second day. The largest 
number examined were on what would correspond to the fourth 
and seventh days, z.e. seven and five; but there were four each 
on the fifth and sixth days. 
It will be observed that these control mosquitoes were not, as 
the other series, collected on one, but on three nights. A very 
slight difference in breeze and light seems to affect the number 
who bite; or any extra restlessness on the part of the birds 
would have the same result. 
In none of these twenty-nine were coccidia found. Of the 
eighteen fed on the Blue Jay with Halteridia, twelve were 
examined from two to six days after feeding and none contained 
coccidia. 
The forms found on the second day measured 6-7 ~, some 
of them a little more. They were oval bodies containing 
scattered granules of black pigment, and had a sharp, clear 
outline. 
T incised the stomach, and by repeated washing and com- 
pression with a cover-glass was able, not only to. wash out the 
contents of the stomach, but even to express the loosely attached 
epithelium, so as to leave the stomach as a transparent clear 
bag. To this outer wall the majority of coccidia remained fixed, 
though in one of the mosquitoes I observed some to escape with 
the epithelium. At no subsequent date could I ever detach 
any by this process, though some coccidia would be ruptured. 
The next morning the smallest measured 10 4; some were 
12m. On the sixth day they were met with up to 304; by 
this time the pigment had absolutely as well as relatively 
diminished. 
In another three days some of them reached 60; and in the 
last of the series examined (tenth day) there were coccidia 
measuring 70 m. 
The coccidia could now be seen to project from the outer wall 
of the stomach ; very few contained pigment, and that in small 
amount. 
Some of the coccidia were clear and others had a granular 
appearance, but in none were there either black spores or 
germinal threads to be seen, 
For the further development the early deaths of the mosquitoes 
from the inclemency of the weather rendered this series useless. 
One of those which were infected on the night of January 5, 
and another infected on January 7, did reach this stage; and 
in the last of those first fed on January 5, which died on 
January 22, ruptured cysts were found by me in the stomach 
wall, as well as numerous cysts containing mature germinal 
threads, and these threads were also found in the body fluids 
and in cells in the salivary glands. 
My observations are, therefore, mainly based on those infected 
November 30 and subsequent dates before my arrival, and on 
some infected December 22. The one infected on January 5 
died on January 19, and the coccidia in it had an appearance of 
striation. 
On adding salt solution (gr. xv. to the ounce) and pressing 
on the cover-glass, a projecting coccidium was ruptured ; and 
the contents poured into the fluid, leaving the cyst wall still 
attached to the stomach. 
The contents were seen to consist of a mass of shrivelled 
threads. This appearance in the other series mentioned I have 
frequently seen. 
NO. 1553, VOL. 60] 
These threads, Ross’s germinal threads, are sickle-shaped 
bodies about 14°15 in length, they stain with logwood or 
methyl blue, but not strongly ; on adding water or Farrant’s 
solution they lose their shrivelled appearance and become more 
rounded. Nearer one end than the other is an unstained 
portion (? nucleus). , 
They show no signs of movement ; but as they are invisible 
in water and only become visible when shrivelled hy the salt or 
stained, it may be doubted if they have been seen alive. 
If a mosquito has its thorax incised when rather older than 
this, similar threads are found in the fluid exuded if salt solution 
is added to it. 
In such a case ruptured cysts are found in the stomach wall. 
The position as regards the salivary gland involves a difficulty 
which is not met with in any other part of the examination. 
The dissection of the stomach is easy ; that of the salivary 
gland in its entirety is not, and for some reason appears to be 
more difficult in the old infected mosquitoes. Any rough 
manipulation results in the detachment of the cells, and little 
more than the duct is left. In most cases, however, one 
entire gland, or portions of both, can be exposed in fair 
condition even in old infected mosquitoes. 
In every case where this was done and germinal threads were 
found in the body-fluids, the germinal threads were also found 
in some of the cells in the salivary gland, and no similar 
threads have I found in a large number of salivary glands 
examined by me in mosquitoes bred from larvae, free about the 
laboratory, or in the earlier stages of coccidial infection. 
The affected cells can be distinguished with a low power, as 
they have a granular appearance, whilst the unaffected cells are 
quite clear. 
With a high power, if not very numerous, the isolated ger- 
minal threads can be clearly distinguished and recognised by 
their peculiar shape and shrivelled appearance (the examination 
must be made in salt solution). If numerous, the individual 
threads can be no more distinguished than in the coccidia, but, 
as in those,‘pressure on the cover-glass will rupture the cell, and 
the germinal threads are then poured out. 
The threads do not fill the cell. There is a faintly granular 
crescentic portion on the side most remote from the duct, which 
in many cases at least is free. The part of the cell in which 
the threads lie must be nearly fluid, as it permits oscillations of 
the threads to take place. 
On these points I have satisfied myself by repeated examin- 
ations, though the appearances are by no means difficult to 
make out ; and have gone at some length into the question, as 
so far we have found no satisfactory method of making 
permanent preparation. All the preservatives at our disposal 
wrinkle up the delicate cells, with the exception to some extent 
of weak formation solution ; and I have no confidence in that 
as a means of making permanent specimens. 
The whole gland is never involved. In one dissection made 
by Ross the cells in both middle lobes and in no other part of 
the gland contained the threads. In several cases where one 
gland has been exposed entire, the middle lobe alone has been 
involved ; but in the majority all that can be stated with cer- 
tainty is that the cells in one portion of the gland contain 
threads, and in other portions they do not. 
The following specific observations made by myself on 
mosquitoes dissected by Major Ross, Dr. Rivenberg of the 
American Missiqgn, who is working with Dr. Ross, and myself 
may be of interest. , 
(a) Coccidial cysts full of apparently mature germinal 
threads, no ruptured cysts, no germinal threads in the 
body fluids or salivary glands. Two observations. 
(4) Cysts full of germinal threads, other ruptured empty 
cysts, germinal threads in body fluids, germinal 
threads in salivary glands. Over twenty observ- 
ations. 
(c) Empty cysts in stomach wall, germinal threads in body 
fluids of thorax. Germinal threads in salivary glands. 
No cysts still containing germinal threads. Two 
observations. 
(d) Empty cysts only in stomach wall, no germinal threads 
in body cavity, no germinal threads in well-exposed 
salivary glands. One observation, the mosquito had 
been infected four weeks before death. 
These observations fully confirm Ross’s statements in every 
point. They indicate that the threads are formed in the coccidia, 
that they escape on the rupture of these into the body-cavity and 
