6 9 
3. Observe chat one end of the ovum is alwavs 
stouter than the other. The stout end contains the 
head of the embryo, and is the end from which the 
young larva escapes. Note also that when Anopheline 
eggs are seen at the side of vessels drawn up by capil¬ 
larity the thick end is at the bottom. Examine the 
surface of the water remaining in the hollow stopper or 
receptacle, and observe that the ova of Anophelines are 
laid singly without any cement substance, and float 
singly or touching one another on the water. 
Fig. 24. Patterns formed by Eggs of Anophelines 
4. Observe star-shaped patterns formed by some 
species, or the arrangement in parallel groups assumed 
by the ova of others (Fig. 24). Note that this arrange¬ 
ment is dependent on physical causes (shape of the egg, 
etc.), and not on the fact that the eggs are laid in such 
positions. This is readily done by stirring up a number 
of Anopheline ova on water, and noting how they tend 
to form groups in triangles and star shapes (p. 186). 
5. Ascertain that Anopheline ova, when first laid, 
are white, but rapidly darken and become black. 
Observe that Anopheline ova are very often laid in 
heaped-up masses, which eventually become dispersed 
by waves, etc. Observe that the eggs then form 
patterns. 
6. Place some half-dried mud in a flat dish, and 
put this inside a piece of mosquito netting in which 
