ON THE AGAMIC REPRODUCTION AND MORPHOLOGY OF APHIS 35 
the Ivy-leafed Geranium which hangs in my study, and for the last 
two months has been regularly giving rise to broods, sometimes 
winged and sometimes apterous, without any appearance of males or 
females. With respect to the external characters of the reproductive 
organs, I have nothing of importance to add to Siebold’s or Morren’s 
description. 
$2. The Development of the Pseudovuim 
The terminal chamber of any of the ceca of the pseudovarium is 
a rounded or oval body (Pl. XXXVI. [Plate 1] fig. 1, A), united by a 
delicate ligament (a), proceeding from its free end, with the ligaments 
which pass from the other czeca of the same side, to form the common 
pseudovarian ligament. The wall of the chamber is a delicate trans- 
parent ‘membrane (4), in which, here and there, rounded endoplasts 
(or nuclei) are imbedded; while others lie on its inner side, con- 
stituting a sort of epithelial layer (c) continuous with the contents of 
the chamber. These, when perfectly unaltered, are constituted by a 
homogeneous pale periplastic substance (@), containing about a dozen 
clear spheroidal cavities (¢) whose walls are a little denser than the 
rest of the periplast. The cavities have on an average a diameter 
of sjJy,th of an inch. In the centre of each is a rounded opaque 
body (7) like one of the endoplasts of the wall of the dilatation, 
and, indeed, obviously of the same nature. 
In whatever fluid I have examined this tissue, it began after a 
time to alter. In the very weak syrup which I ordinarily employed, 
the change consisted partly in the slightly increased definition of the 
walls of the clear cavity, but more particularly in the breaking up of 
the periplast into spheroidal masses, each of which contained a single 
vesicle and its endoplast.1. The resemblance of such a body to an 
ovum with its germinal vesicle and spot is complete; nor would it 
be possible for any one ignorant of the origin of the body to say 
that it was other than an ovum. Water instantly alters the appear- 
ance of the tissue, completely destroying its distinctive character. 
Dilute glycerine shrivels up the vesicles and alters the appearance of 
their central endoplast, probably by endosmose. Acetic acid renders 
the periplast dark, and gives an exceedingly marked definition to the 
parietes of the vesicle. To see the appearances I have described as 
normal, the part must be examined perfectly fresh, and in a solution 
of sugar neither too dilute nor too concentrated. 
In certain specimens the contents of the lower part of the terminal 
1 Leydig (Zc. p. 63) appears to regard this as the first state of the ovigerms, and he has 
overlooked the epithelium. 
D2 
