ii6 
by chloroform vapour or by £ concussion 5 in a test tube. 
2. Fix in (a) acetic-alcohol for five to ten minutes 
(glacial acetic acid one part, absolute alcohol six parts, 
chloroform three parts), wash in absolute alcohol till 
free from acid. (It is often advisable, especially with 
thick flies, to nick the chitin at some unessential part 
in order to allow penetration of the fixative.) Or 
(b) sublimate-alcohol (p. 404), or ( c ) absolute alcohol, 
fifteen minutes. 
3. Place in one per cent, celloidin for a day and 
in three per cent, celloidin for another day. These times 
may with advantage be increased, but sometimes a 
few hours only suffice. (The solution of celloidin 
is made by dissolving dry chips in 50 c.c. alcohol and 
then in a day or so adding 50 c.c. ether.) 
4. Transfer to cedar-wood oil, and when the 
mosquito sinks transfer to— 
5. Paraffin for half to one hour and then proceed 
as before (p. 46). 
The Examination of Separate Organs 
1. Remove the mid-gut or the ovaries or the 
salivary glands and fix in sublimate alcohol or Zenker 
(ch. xxxiv), and proceed as on p. 46. 
2. The salivary glands can thus be studied by 
embedding only the head and thorax ; zygotes by 
embedding only the abdomen or the dissected-out gut. 
The times for the dissected organs in various 
fluids is very short, only five to ten minutes in each 
fluid. 
3. Stain with haematein (p. 408). 
LITERATURE 
Grassi : The studies of a Zoologist (in German or Italian). 
