16 Journal of the Asiatic Society of Bengal. [N.S., XIX, 
The head of the living insect was cut off and allowed to 
remain for 30 hours in the fixative of Carnoy and Lebrun. 
Then the head was put in 90% alcohol for 5 to 6 days. In 
absolute alcohol, a few hours’ (4 hours) immersion was found 
sufficient to dehydrate it completely. Then taking it through 
a mixture of absolute alcohol and chloroform it was placed in 
pure chloroform for 48 hours. Thence it was heated in molten 
paraffin for 4 hours. Sections of 6 » to8 » thickness were cut 
and stained on slide, with Heidenhain’s iron haematoxylin. 
Delafield’s haematoxylin and eosin in 90°, alcohol were also 
tried. 
For the internal organs—digestive, nervous and reproduc- 
tive—besides alcohol, various other fixatives and preservatives, 
among them the following, were tried :-— 
(1) Bouin’ 8 fluid— 
fixed for three days and washed in 90% alcohol and 
preserved in 75% Alcohol. 
(2) Picro-acetic acid— 
for 24 hours, washed with 70% alcohol to 
which pier of lithium had been added; 
preserved in 75% alcohol. 
(3) Picro-nitric acid— 
fixed for 15 hours, washed and preserved as in No, 2. 
(4) Formaldehyde 40%........ 10 vols. 
Be OI Fo lons coke 90 vols. 
In the case of the digestive system, formol-alcohol 
gave as good results as any of the first three. But for the 
study of the reproductive organs, Bouin’s fluid and picro- 
acetic acid were found to be more suitable. 
The investigation of the respiratory system presented 
many difficulties. The tracheae, being of the same pale colour 
as the surrounding fat tissues, could not be easily distin- 
guished. To make them rg ada the following method 
of injection was employed: 
e insect was placed in a tube containing a solution of 
Indian ink, which was kept in a flask whose mouth was connected 
to an aspirator. When the air contents of the flask and tube 
and ultimately of the tracheae were exhausted, the ink was 
forced into the empty tracheae. The insect was then treated 
with 5% KOH for 24 hours; this treatment dissolved out all 
the soft tissues, leaving the chitinous (black) tracheae in situ 
behind. 
The habits recorded here are mainly from my observations 
in the experimental cotton fields at Pusa. 
The insect is bisexual and the male, which is comparatively 
smaller Ss the female, is chosen for descripti ion 
measurements given in the text are the average of 
the bemces ge at least 10 freshly killed specimens. 
pT RN 



