F. M. Howlett 
489 
their condition (as regards moisture) better than the same number of 
dead ones, and if a certain degree of over-crowding is unavoidable, it is 
sometimes better merely to stupefy the insects and let them revive in a 
box or tube, and to kill at the journey’s end. If of fair size, a little 
pad of soft paper above each (dead) insect is useful in absorbing 
moisture. 
For closing tubes or bottles containing formalin-specimens, Mr Gordon 
Merriman has shown me a method which is both ingenious and efficient 
(Fig. 3). A plug of plasticine (cheap and easily obtained) is pushed 
right down on to the surface of the liquid, until the latter spurts up 
through a pin-hole made in the plug, all the air in the tube having 
previously escaped through the same hole. The hole is then sealed by 
a wipe of the thumb, and the liquid remains completely filling a per¬ 
manently closed tube, preventing all damage from shaking. For closing 
bottles which contain specimens in any fluid preservative, and which 
will not require to be opened for a long time, “ Viscose ” bottle-caps 
(obtainable from chemists) seem admirably adapted, but they must be 
kept in a special fluid solution till used. 
