620 
ME. LEBBOCK ON THE OENEEATIYE OEG-ANS, AND 
Below the eggs was a yellow matter, corresponding apparently to the so-called corpora 
lutea found in the egg- tubes of insects. 
The mature egg is elongated fusiform, about ^s^l^hs of an inch in length, and 
enclosed in a tough, somewhat transparent chorion. 
The Purkinjean vesicle, which in the smallest egg-germs was sometimes even less than 
Xo-Q-oth of an inch, increases to as much as of i’^oh in diameter. In the 
meanwhile the macula has undergone important changes. 
I have already mentioned that on its first appearance it is a single, apparently solid 
body; but even in the smallest egg-germs the Purkinjean vesicle contains very often, 
besides the macula, a small vesicle, which increases in size with the macula, but other- 
wise undergoes no alteration (Plate XVII. fig. 40). In many cases, however, I could 
not see this secondary macula. 
The macula itself soon appears to develope in its interior a clear space (Plate XVII. 
figs. 40, 41), which is apparently bounded by a membrane, since after a time it works its 
way to the surface of the macula, and forms a projection, and, indeed, sometimes appears 
to detach itself altogether from the macula. It is always quite clear and transparent, 
Avhile the macula itself is turbid, though at this stage it again contains a clear space 
in its interior. I examined the Purkinjean vesicles of six full-grown eggs, but was 
unable to satisfy myself as to the normal state of their contents at this stage. All of 
them contained the large macula, which in some of them had the form of a hollow cap. 
Two of them had a second clear macula, about half as large as the first (Plate XVII. 
fig. 40) ; and one contained a number of small vesicles. These changes may be compared 
with what takes place in Geophilus. 
The yelk consisted, as usual, of a viscid substance, containing fine granules and oil- 
globules, varying up to xrfo'otti of an inch in diameter. Acetic acid acted in the usual 
manner on these tissues, and dissolved all the granules contained in the free nuclei 
(which I supposed to be embryonic Purkinjean vesicles), just as it does the true macula. 
Dilute ammonia also dissolves the macula and the granules of the free nuclei. 
The spermatozoa have a minute pear-shaped head and a long tail. Taken from the 
testis of the male, they exhibit a wriggling movement. 
General Eemarks. 
It appears that in the Annulosa, as in the other divisions of the animal kingdom, the 
Purkinjean vesicle is the first-formed part of the egg, and that the yelk and vitelline 
membrane are subsequently deposited round them. This holds good (according, at least, 
to the various naturalists who have written on the subject) in most insects, in Crustacea, 
Spiders, Ladnularia and other Rotatoria, in Hermella, in Oxyuris, Ascaris, and the 
Xematoidea generally. Dr. Allen Thomson, indeed*, extends this to the whole animal 
kingdom. “ The germinal vesicle,” he says, “ is universally the first part of the ovum 
which makes its appearance ; it does not appear to be nucleated or to possess its macula 
* Article “ Ovum,” p. 133. 
