AND ZYGOTES IN MOSQUITOS INFECTED WITH MALARIA. 9) 
(e.) If the normal structures of the stomach are known there is no difficulty in 
recognising zygotes.” (Fig. 4.) 
Avs le fibyes i 
a a AG Eb Relvm 
| CS 
Srs SN 
a Ne Oy 
IIR 
Z 
Leas 
Large Ry gale Air capillaries Eprthelwm cells 
Fig. 4.—Microscopic appearance of mid-gut, showing cell-structure and zygotes. 
(1.) The younger forms are clear oval or round bodies 6-7, é.e., about the size 
of a red corpuscle, containing definitely seen pigment granules. 
(2.) The larger forms have a distinct cyst wall (oocysts) and still retain pigment 
which is unmistakable. 
(3) The largest oocysts have lost their pigment and are clearly defined cysts 
(40-60) filled with hundreds of sickle-shaped bodies (sporozoits) which escape on 
rupture. 
(f.) “ Black spores” (Ross).—Although very many dissections of Anophelines 
were made by Christophers and myself in Africa, these brownish or black 
sausage-like bodies which sometimes are found in the large oocysts were never 
seen by us. In India we saw them only twice, in hundreds of dissections, and on 
both these occasions they were in the region of the salivary gland. They are, 
however, far commoner in the oocysts of Culicines fed on Proteosoma. According 
to some authors they are parasitic sporozoa, but nothing is known as to their 
life-history. 
Staining of Zygotes. 
(a.) Draw some 10 per cent. formalin solution under the cover-glass by means 
of blotting paper, and float off the cover-glass carefully. The stomach will 
probably remain attached to it. 
(6.) Wash in water. 
(c.) Stain lightly with methylene blue. 
(d.) Wash in water, dehydrate, clear in xylol. 
(e.) Mount in balsam. 
Good preparations are easily obtained in this way. 
~ Lygotes if scanty (1 or 2) will be found at the bottom end of the stomach nearest the 
Malpighian tubes. 
