HISTOLOGY OF FEMALE ORGANS 83 
“The pericardial cells are extremely large cells lying on either side of the 
dorsal vessel throughout its whole extent. They are by far the largest cells in 
the mosquito, varying from 30» to 50 in longitudinal diameter. They are 
elongate or pear-shape in form, and contain several nuclei. The nuclei usually 
show signs of degeneration. The peripheral portion of the cell stains more 
deeply than the central portion, which contains the nuclei and small stained 
granules. There is a considerable number of masses of a light yellowish pigment 
resembling that found in the large visceral ganglia cells. The fibres from the 
branches of the alary muscles pass over and around the pericardial cells to reach 
the dorsal vessel. From their structure and situation the pericardial cells 
appear to be of the nature of ganglion cells. 
“ The Fat-body.—The fat-body, both where it occurs as a portion of the body 
wall and where it lies as free lobulated masses, consists of cells containing 
numerous oil globules. The cells are of considerable size, and their borders may 
be frequently traced as polygonal areas. The nuclei are oval in shape with a 
central mass of chromatin and chromatin threads. Besides oil globules the cells 
contain granules staining with hematein, and minute droplets of a highly re- 
fractive, dark substance, which gives the appearance of pigment. These drop- 
lets are larger in amount in old mosquitoes than in those freshly hatched.” 
THE REPRODUCTIVE SYSTEM. 
“ Hach ovary consists of a large number of follicular tubes whose lower ends 
open into the ovarian tube, and whose upper ends terminate in a delicate sup- 
porting filament (terminal filament). The apex of the ovary is formed of a 
single follicular tube, whose filament is attached to the fat-body of the fourth 
segment, 
i Aeon the whole ovary there is a delicate nucleated sheath. 
“ Hach follicular tube contains one or more egg-follicles in different stages 
of development. In the freshly-hatched mosquito each follicular tube contains 
an undeveloped egg-follicle. As this develops, a second and a third undeveloped 
follicle appear above it, which again undergo development into mature eggs. 
The follicle at first consists of two to four large cells, with large nuclei sur- 
rounded by a single layer of smaller epithelial cells. 
“The central cells then increase in size and number, so that many very large 
cells are contained in the now enlarged follicle. The surrounding epithelial 
cells also become larger, and rapidly increase in number so as to form a layer 
of regular cubical cells surrounding the follicle. The central cell nearest the 
ovarian tube is the ovum, the rest are nurse cells, and eventually disappear. 
Both the ovum and the nurse cells increase greatly in size. 
“ Frequently in Anophelines a large portion or the whole of the adult ovum 
consists of a mass of Sporozoa. These consist of numerous small cysts, each 
containing eight round or crescent-shaped bodies, each with a central chromatin 
spot. 
Me The ovarian tube arises in the centre of the ovary, and receives on all sides 
the follicular tubes. It is lined with a single layer of small cubical epithelium. 
After passing out of the ovary, a considerable number of striated muscular fibres 
are arranged in a loose net-work around it, and pass from it to surrounding 
structures. ; ’ 
“The spermatheca consists of a chitinous sac, with large cells lying externally. 
These resemble the cells of the cuticle, and contain droplets. They do not cover 
the whole of the surface of the spermatheca. The spermatozoa have a narrow, 
slightly-curved head and a long tail. The duct of the spermatheca is narrow and 
thick-walled, and contains muscular fibres. Certain large cells lie in connexion 
with the duct externally. The mucus gland contains cells filled with secretion.” 
7 
