164 Dr. R. Leuckart on the Asexual Reproduction 
and down in the cavity of the body with the neighbourmg organs. 
In general these balls are pretty symmetrically arranged, and 
placed at the same level; but sometimes one or the other of 
them is more approximated to the median line, or placed a little 
forward. ‘ 
When the body of the larva is torn up, we soon ascertain that 
these balls do not float freely in the body-cavity like the germs 
which sueceed them, but are affixed to two Malpighian vessels, 
by means of a pair of longer or shorter, thin ligamentous cords. 
In general the point of attachment is not far from the msertions 
of the vessels, and indeed usually rather higher on one side than 
on the other. Sometimes a thin filament is seen passing back- 
ward from it. 
Under a higher power(fig. 2) we may distinguish in the balls a 
delicate structureless env eloping membrane, and a number of clear 
vesicular cells of 0°01—0°017 millim. in diameter, which lie in a 
finely granular pale protoplasm, and according to their size en- 
close one or more (three to five) likewise vesicular nuclei 
(0-006 millim.). 
When the investigation 1s extended to a greater number of 
larvee, those being especially selected which have already quitted 
their origimal dwelling-place, it 1s soon discovered that these 
structures do not ali possess the same constitution. Not only do 
they gradually increase and change their form to an oval, but, 
further, at a certain size (length 0:067, breadth 0°042 millim.) 
they are repeatedly and irregularly constricted and acquire a 
form (fig. 3) by which one is involuntarily reminded of the ap- 
pearance of a lobate embryonic kidney. The lobes which are 
separated by the constrictions prove on closer examination to be 
the peripheral segments of balls, which are flattened on their 
contiguous surfaces, but otherwise have a globular form and a 
diameter of 0-02-0:025 millim. 
In their interior these contain according to their diameter a 
larger or smaller number of vesicular nuclei (of 0°007 millim.). 
In the largest balls as many as from sixteen to twenty of these 
nuclei may be counted; and here we may also further ascertain 
that each of them bears a clear superficial layer more or less dis- 
tinctly defined, and has thus become the central point of an in- 
dividual cell (fig. 3). 
On comparison with the previous stages of formation, it appears 
beyond a doubt that these balls represent a further development 
of the vesicular cells formerly described. By displacement of the 
mtercellular substance originally present, these cells have gradu- 
ally mereased and become mother cells by formation of brood 
cells in their interior. The original cell-membrane persists, in 
the form of a structureless bounding membrane, which has only 
