424 
PROF. B. T. LOWNE ON THE STRUCTURE AND 
At this stage the ovary is pear-shaped ‘25 m. in diameter and 
34 to *4 m. in length. It is enclosed in a thin hut perfectly dis- 
tinct cellular capsule ( c ). It consists of a stroma of small cells 
less than 5 jj, in diameter, enclosing the bundle of egg-strings (e.s). 
These are closely packed together and occupy the anterior rounded 
half of the ovary. 
The posterior narrow part of the ovary (cl) is filled with small 
round cells precisely like those which form the egg-strings, except 
that the latter are slightly larger, 5 p. 
The egg-strings present, even at this period, a narrower con- 
stricted posterior and a more dilated anterior portion ; they are 
like long narrow flasks, the neck measures 5 /x and the dilated 
portion 15 p. in diameter. The whole consists of small closely 
packed cells enclosed in a fine cuticular membrane. The necks 
of the egg-striugs appear to be open behind, where the cells of 
the posterior part of the ovary, destined to form the duct, are con- 
tinuous with those within the flask-like egg-strings. There is as 
yet no trace of a lumen in the solid rudiment of the oviduct. 
The cells between aud around the egg-tubes are, however, 
already distinctly elongated and form a stroma, in which the egg- 
strings lie, so differing entirely from the cells which form the 
egg-strings and fill the calyx of the ovary. 
The next stage of development is seen in the half-formed pupa, 
about the tenth day (Plate XXVIII. fig. 5) ; at this stage the ovary 
is apparently cup-shaped, it appears crescentic in lateral sections, 
with the concavity of the crescent in front ; it lias a diameter of 
*5 m., but is still about ’3 m. in thickness, measured from before 
backwards in its thickest part. That part of the ovary not 
occupied by the egg-strings is excavated by numerous chan- 
nels ; these form the calyx of the oviduct aud cover the whole 
convex surface of the orgau. The egg-strings are now so broad 
in front that I shall term them egg-follicles. The egg-follicles (os.) 
are ovoid masses of small cells, each with a very narrow stalk (st.) 
The stalk is apparently filled by a single row of cells, and its 
investing cuticle is frequently transversely wrinkled, which often 
produces an appearance of striation. Possibly this may have 
given rise to the very remarkable view held by Schneider (23) 
that the egg-tubes are developed within the alar muscles of the 
dorsal vessel. 
Each rudimentary egg-follicle is now surrounded by a pouch, 
