AucusT 3, 1899] 
NATURE 
222 
III 
had a bay hybrid richly striped ; the other a hybrid with but 
indistinct stripes. The subsequent foals—one by a chestnut 
thoroughbred horse (Tupgill), the other by a hackney pony (Mars 
Royal)—are bays, not only devoid of stripes, but affording no 
indication whatever that their dams had been previously mated 
with a zebra. ; 
Although I experimented with seven English thoroughbred 
mares and an Arab mare, I only succeeded with one—a small 
chestnut. This mare produced twin hybrids last summer ; 
she has this summer a foal to a thoroughbred chestnut horse 
(Lockstitch). One of the twins died soon after birth, the other, 
richly but unobtrusively striped, in its colour and make strongly 
suggests his dam. The chestnut mare’s new foal neither in 
make, colour nor action in any way resembles a young zebra 
nor a zebra hybrid. In 1897 a bay mare by a bay Arab horse 
(Hadeed) was for some months in foal to the zebra. Since she 
miscarried in 1896 she has had two foals to a thoroughbred 
horse (Lockstitch). Neither of these foals in any way suggests a 
zebra. In this case the unused germ cells of the zebra had pre- 
sumably a better chance of reaching the ovum from which the 
first of the two pure-bred foals was developed than is usually the 
case. 
Attempts were made to cross Welsh, Exmoor, New Forest, 
Norwegian and Highland ponies with the zebra without success, 
and though a cross-bred Clydesdale has twice had a hybrid, she 
has not yet produced a pure-bred foal. The experiments, as far 
as they have gone, afford no evidence in support of the telegony 
hypothesis. 
INVESTIGATIONS ON MOSQUITOES AND 
; MALARIA.» 
] I{AVE the honour to report the results of my observations 
since my arrival here on December 21, 1898. 
Major Ross, I.M.S., first demonstrated and explained to 
me hismethod of dissection of the mosquito and the structures 
normally met with. From prepared specimens he then showed 
me the bodies met with after feeding these mosquitoes on birds 
infected with the proteosoma and the change day by day which 
they showed, ending with a demonstration of the germinal 
threads in cysts in the stomach wall, as seen in the fluids of the 
body and in cells in the salivary gland. 
On my arrival there were in the laboratory, in test-tubes, 
series of mosquitoes fed on birds infected with proteosoma on 
the night of November 30, December 10, December 12, 
December 15, and December 20. 
Of each of these series Major Ross dissected specimens for 
me after killing the mosquitoes with chloroform, and again 
demonstrated in these the same bodies that he had already 
shown me in prepared specimens ; pointing out and demon- 
strating as he went on that in the older mosquitoes it was 
possible on cutting the thorax to observe the nature of the con- 
tents both of the coccidia in the stomach and of those of the 
cells of the salivary glands. 
The points showed to me I readily observed. 
From series of mosquitoes before mentioned I day by day 
examined both those which died and others I killed, and was as 
readily able myself to repeat the observations and in the earlier 
series to trace the changes in the size and nature of contents of 
the coccidia. 
I also examined a large number of mosquitoes caught about 
the laboratory, and others which had been raised from larvz. In 
no case did I find either coccidia in the stomach wall, germinal 
threads in the body fluids, or in the cells in the salivary gland ; 
nor did I find “ black spores” in them. 
Major Ross informed me that his published results were 
based on observations made in the hot season when the temper- 
ature was So* F., or more ; and that now I should find the changes 
considerably slower, as it was the cool season, but that the 
sequence of events was the same. 
My observations on the mosquitoes fed on December 20 and 
December 15 showed that this was the case, and that the 
coccidia advanced more slowly than the published results 
indicated. He also informed me that mosquitoes fed less readily 
and more difficulty was met with in rearing them to a spore- 
bearing age. 
1Dr. Daniels’s Report to the Secretary of the Malaria Investigation Com- 
mittee of the Royal Society, London, on the results of observations made 
by him in Calcutta in conjunction with Major Ross, I1.M.S. Dated 
Calcutta, January 23. 
NO. 1553, VOL. 60] 
These difficulties the use of the incubator was only partially 
successful in obviating. 
On the evening of January 1, following exactly in Major 
Ross’s lines, I commenced a repetition of his main experiment. 
Two mosquito nets, free from rents, were taken, and in them 
vee released a large number of grey mosquitoes reared from 
arve, 
In the one, four birds were placed; in three of them on 
December 31 I had found proteosoma in large numbers, and in 
the fourth a moderate number. 
In the other net two birds, in whose blood no proteosoma 
had been found, were placed ; these two died two and three 
weeks later, and no pigment was found in their organs, and 
repeated examinations of their blood had failed to show 
proteosoma, 
On January 2 none of the mosquitoes had fed, and on 
January 3 only two in the first net and eight in the second. 
On January 4, a warm night with a minimum temperature of 
59°2° F., sixty-three mosquitoes were found gorged with blood 
in the morning, and were caught in separate test-tubes plugged 
with wool and placed in the incubator. Eighteen in the other 
net, where the non-infected birds were placed, the control 
series, were similarly collected ; these were caught in the same 
manner and treated in the same way. 
On the following two evenings, with minimum temperatures 
of 60°7° and 63'2°, sixty-eight and forty-six mosquitoes were fed 
on the infected birds and were kept for the preparation of 
specimens. Twelve mosquitoes were fed on the non-infected 
birds, and were used as additional controls so as to bring the 
number of the control on Blue Jay with numerous Halteridia. 
On the third day the sixty-three, with the exception of those 
killed for examination or dead, were released inside a clean net 
free from mosquitoes, and birds free from proteosoma were also 
placed in it. 
In the morning all mosquitoes found inside were collected, 
and most of them had fed well ; the minimum temperature was: 
63825 Bs 
This is the method Ross employs to re-feed the mosquitoes. 
If infected birds are used, you get a younger generation of 
coccidia ; so I used sterile birds. The method works fairly 
well in warm weather; but there is always some loss, as the 
full number are not collected again in the morning. As the 
process is repeated over and over again, this loss becomes 
serious, the more so the longer the period required for matur- 
ation. In a frequently repeated process of this kind there is 
always the possibility of an outside mosquito getting in. 
The mosquitoes were not fed on the following night, as they 
were full of blood; but most of them voided it during the 
night, and many died next day. 
The remainder were given the opportunity of re-feeding 
every night after this; but a spell of cold weather ensued with 
minimum temperatures of 44° F.-49° F. ; only on one night 
did it exceed 50° F.,and on these nights few fed well or at all, 
and there was a consequent continued heavy mortality, only 
one being alive on the tenth day, and that subsequently escaped 
in the night. 
This method of feeding is very unsatisfactory in exceptional 
weather of this kind; the mosquitoes in the day are kept 
warm in the incubator, and rapidly digest their food, whilst at 
night the cold renders them torpid and they do not feed. 
The control mosquitoes were treated in exactly the same 
manner and fed on birds free from proteosoma. The last died 
on the thirteenth day. 
The results of the two series are as follows :— 
Sixty-three fed on proteosomal birds. 
Forty-nine examined, three reserved for sections, one too 
much decomposed for satisfactory examination. 
Ten not accounted for, lost in the nets. 
Of the forty-nine examined, two were killed on the first 
day—that is, under twenty four hours, and possibly under twelve 
hours, after they had fed. No coccidia were found in these. 
Two more were examined the following morning, under thirty- 
six and possibly under twenty-four hours after they had fed ; no 
coccidia were found in these. : 
In two examined about 4 p.m., the minute pigmented coccidia 
were found ; that is, under forty-six and possibly not more than 
thirty-four hours after they had fed on the infected birds. 
The remainder were examined on the following days, the 
largest numbers, eighteen, on the fourth day and twelve on the 
seventh day, as on these two days those numbers died. 
