Nov. i, 1894.] THE TROPICAL 
AGRICULTURIST. 
291 
2nd — I have had some slimy stagnant water from 
drains brought in and put into a bottle with a frog 
and placed two leaves of the Adhatoda V. in it. 
The leaves in a measure did disintegrate the stuff 
in the water, had no effect on the frog, but did not 
c ear the water, the water remained of a greyish 
yellowish colour. 
3rd—! had a nnmber of Mosquitos brought in and 
placed in a box with top and bottom covered with 
net, the infusion was freely used twice (leaves soaked 
for 24 and 48 hours) it seemed to have no effect on 
the Mosquitos beyond in a way stupifying them. I 
had some dozens in the box for a day and a night ; 
they were twice wetted with the infusion — strength 
1 Id. to 1 gallon water — they seemed lively enough 
at evening, but were all dead in the morning. Now 
ibe question arises — what is the duration of a Mos- 
quito s life? how long does it live? did they die a 
natural death? or w^re they killed by the infusion? 
I have not so far found, after my experiments on 
tea bushes, and dead Mosquito's or even full grown 
ones, but any number of young ones in, I should 
say, a state of coma. Only in one case have they 
returned to the same bush and that after a lapse 
of nearly a month — they decidedly leave the bush 
after it ha? boen syringed, but whether they die, 
cr take hmg flights I have not been ab e to ascertain. 
I have now tried some 20 patches attacked by this 
blight, and in every case they have disappeared after 
4 to 6 applications. They are easier got rid of in 
dry than in wet weather,— Yours faithfully, 
(Signed) F. C. Moran. 
Simla, dated August 1st, 1894. 
To F. 0. MoRAN, Esq., Khouikor Tea Estate, 
Dibrugarh, Upper Assam. 
Dear Sir.— Yours of the Kith, as also your samples 
of leaves, reached mo hero yesterday. It is a little 
difficult to identify the plaut by leaves only, as a great 
number of the Acmitkacece are almost identical in 
their foliage. The leaves sent by you are a little longer 
and narrower than those of the plant iu Bengal, but 
still I suspect they may be the correct thing. The 
JBeugal Adhatoda, on being dried nearly always turns 
a yellowish brown colour and the leaves are generally 
thicker and smaller than in your sample. If not tlie 
right plant, since it belongs to the same family 
undoubtedly, your experiments would point to the 
same property being possibly possessed by otber Acan- 
tkacea- than Adhatoda. 
2. Your experiments with life-infested water, I do 
not think very statisfaetory. If the water chanced to 
contain mineral impurities, as woll as animal and 
vegetable forms of life, the Adhatoda would not clear 
it of the mineral matter. What you should have done 
was to have taken two clear glass jars and to have 
rilled these with the self same water at the same timo. 
You should have next examined the contents of both 
with a low power microscope to see if they were equally 
infested with the same forms of life. Then you 
should have put into one of the jars a few leaves 
squeezed or broken a littlo or a measured quantity 
(to be recorded) of your standard infusion. After, say, 
2 or 3 hours you should have then examined both 
fluids to soo the action comparatively. By 4 to 5 
hours (according to my results) the jar treated with 
Adhatoda would have been found to have had all 
the contained minute organisms not only killed but 
tntofe or less decomposed, and the water thus cleared 
cf these impurities, while such higher forms of life 
as a frog or lish would bo 6een to have remained 
unaff ected. The drug is in other words perfeetly harm- 
less On the higher forms of both animal and vege- 
tal)] e life. 
;!. To obtain satisfactory evidence your experiments 
must 1 mparative. Since the minute forms of life 
are found to remain iu the jar of water not treated 
with Adhatoda — a jar filled From the self same source 
and at the same time as t hat which had been treated 
— the comparison would show that whatever change 
hnil been effected in the jar treated with the insecti- 
cide must bo attributed to the Adhatoda, since all 
tlfl conditions remained the same. Even if you do 
not chance to possess a microscope, by which to 
examine the minute forms of life in the water, two 
jars, the one to compare with the other, would bo 
preferable to working with one, the more so if they 
both contain visible (that is, to the naked eye visible) 
green slimy algai, the destruction of which could be 
recognized. Moreover, in a day or two the one jar 
would be seen to contain life, its contents would gra- 
dually get darker coloured, the algce would begin to 
stain the glass by growing upon it and the proportion 
of life to visibly increase, whereas if Adhatoda had 
killed the lower organisms, no such further growth 
would take place, and the one fluid as compared with 
the other would then appear cleared. It was in this 
sense that I used the word "cleared," not cleared in 
the sense of having all animal, vegetable and mineral 
matter precipitated. The expression cleared or purified 
was intended by me, when originally used, to be a 
literal translation of the expression emploj-ed by the 
Sutlej valley cultivator, when he drew my attention 
to the fields that had been treated with Adhatoda as 
compared with those that had not been so treated. 
4. I do not for a moment think that on being 
syringed", the bushes should be regarded as for ever 
after freed from Mosquito. On the contrary, that would 
necessitate that the tea leaf had been so saturated that 
it was permanently poisoned to the Mosquito and pos- 
sibly thereby injured iu flavour as an article of human 
consumption. If 50 square yards in the middle of a 
badly infested plantation be treated, it might be but 
a matter of a few days only when the cleansed portion 
would be again attacked from the neighbouring bushes. 
But I do not doubt that assuming that Adhatoda has 
been found a specific against Mosquito and other such 
pests, the systematic treatment of all and every portion 
of the plantation where these insects appear should 
in time result in their complete extermination. 
5, Your experiment with Mosquito in a specially 
prepared cage I don't think very satisfactory for the, 
same reason as detailed in paragraph 2 and 3. You 
should have made two cages at least, and placed them 
under identical conditions, the one with the leaves 
syringed and the other not. The question you raisa 
as to the cause of death of the Mosquito would have 
then been placed beyoud doubt. Your observations 
on the general effect on bushes treated in the plant- 
ation are more instructive than your specific experi- 
ments. The remarks for example, that " they deci- 
dedly leave the bush after it has been syringed," 
and again that " I have now tried some 20 patches 
attacked hy this blight and iu every case they have 
disappeared alter 4 to 6 applications," show that the 
subjects is well-worthy of thorough investigation. I 
would recommend you to try the following method 
of substantiating these observations. Select two plots 
as remote from each other as possible, and each in 
the middle of badly infected portions of the estate; 
Syringe them both at the same time and to the samo 
extent, the one with pure water and the other with 
the Adhatoda infusion. This w^ould prove whether the 
mechanical action of syringing or the substance used 
as an insecticide possessed the action attributed 
to it. But even such an experiment would havo 
to bo repeated many times and b}- different observers 
in order to obtain an absolute opinion. So far aa 
I can see, it is more important to ileal with the in- 
fant or even the egg, than the perfect insect, and if 
those were destroyed by Adhatoda the pest could at 
all events be thereby controlled. This might be solved 
by syringing young twigs that are seen to possess! 
the eggs, — some with one dose, others with two, &c., 
and then placing those twigs in cages or by carefully 
tying them within muslin cloth (without separating 
the twisrs from the plaut) in order to seo if subse- 
quently the mature insect escaped from the eggs. 
C>. Von ask me as to the duration of the mature Mos- 
quito life, I have read through every article that, 
1 can liud on that subject, and have failed to procure 
you the required information. This point might easily 
be solved, however, by cultivation iu a cage, such 
as that mentioned in my former letter and as already 
indicated iu paragraph above. The late Mr. Wood- 
Mason (as you doubtless are aware) wrote a paper 
on the Tea. mite and Tea-bug. He published thereby 
certain interesting contributions to our knowledge o{ 
