macrogamete undergoes no apparent change. Presently, however, it gradually alters in shape, becoming oval, elongated, and finally assuming a lanceolate and then a vermicular form, the hæmozoin accumulating at the broad or posterior end whilst the anterior end becomes pointed and hyaline. On the completion of these changes, the little body begins to move about, at first slowly, then more rapidly, the pointed end being in front. Should this travelling vermicule, technically known as an oökinete, impinge on a blood corpuscle, white or red, it passes through it.
Fig. 11.—Section of mosquito.
Mouth: b, pumping organ; c, œsophagus; d, homologue of proventriculuse, anterior part of midgut; f, midgut; g, pylorus; h, pyloric diverticulum; i, hindgut; j, rectum; k, Malpighian tubes; l, salivary duct; m, salivary gland; n, dorsal vessel; o, supra-œsophageal ganglion; p, sub-œsophageal ganglion; q, conjoined ganglia; r, abdominal ganglia.
Dissection of the mosquito.—To follow the evolution of the malaria parasite the student, by frequent dissection, should first familiarize himself with the normal appearance of the internal organs of the mosquito. The following method of obtaining and mounting the organs for microscopical examination is that taught by Dr. Daniels at the London School of Tropical Medicine: Having killed the mosquito by chloroform, tobacco smoke, etc., with a mounted needle transfix the thorax, and with the fingers pull off the legs and wings one by one, being careful to pull them obliquely from the needle. The body of the mosquito should then be placed in a drop of normal saline solution on a glass slide. Then flatten
of the intracorpuscular parasites of man and the lower animals, that a similar arrangement obtains in the Plasmodidæ of man. Prof. Grassi showed me sections of the mosquito's stomach in which the travelling vermicules could be seen approaching and actually in contact with the epithelial coat. These preparations were from mosquitoes killed thirty-two hours after feeding on malarial blood.
