ox THE EOEMATION OF THE EGO IN THE ANNHLOSA. 
601 
looks as if it contained one or more nuclei imbedded in a darker substance. Moreover, 
in addition to the large macula, which is generally more or less vesicular, there is a 
smaller one, as in Glomeris. This latter is perhaps to be compared with the small 
vesicular macula of Aclieta. 
In August the luli which I examined contained no mature eggs ; so that they do not 
appear to be so foixvard as those of Polydesmus. 
The cells forming the follicles, or at least their nuclei, could be well seen ; and the 
cells themselves are indicated by small projections along the edges of the follicles, but 
their walls are so delicate that they can seldom be seen in a full view. From the mode 
of examination adopted by Mr. Newport, the histological structure of the follicle-wall 
quite escaped his observation. 
In the mature eggs the yelk contained, 1st, globules of all sizes up to ToWo^h of 
an inch ; 2ndly, greenish spherules -g-w oo th to iiich ; and 3rdly, the usual 
intermediate substance. The large yelk-globules are quite round, but they are not 
liquid, and on applying pressme they split at the edges. Sometimes a globule has 
a single fissm*e ; but very often the splits radiate from the centre, or rather proceed 
inwards from the edges towards the centre. 
In mature eggs Mr. Newport saw a “transparent globular vesicle,” which he assumed 
to be the “proper germ-vesicle considerably enlarged;” this, however, is certainly a 
mistake, since the true Purkinjean vesicle has always disappeared by the time the egg 
is full-grown ; and the vesicle in question is therefore probably the embryo-cell. As 
regards the final lot of the Purkinjean vesicle, I have as little in lulus as in the other 
Mjuiapods been able to come to any satisfactory conclusion. The largest eggs in which 
I could satisfactorily see the Purkinjean vesicle were about -g^-oths of an inch in dia- 
meter ; and the largest vesicles were about of iiioh in diameter, clear, trans- 
parent, and with a single nucleus. The macula in lulus does not, therefore, break up 
into numerous smaller maculae, as is the case in Lithohius and, according to WiTTiCH, 
also in Spiders ; or if this does take place, it belongs to a later period. 
The yelk does not contain any vitelligenous bodies ; but in a great many cases, where 
the yelk was beginning to darken, I observed in it an irregular, yellowish, granular 
patch. This patch was too irregular and amorphous to be of much functional import- 
ance, and at the same time so generally present, that it could not, I think, be altogether 
without significance. The patch is of a more or less oval form, and smaller than the 
Purkinjean vesicle, though somewhat larger than the macula ; it is not present in very 
small eggs, nor in those which have become quite opake. I am inclined to look upon 
it as corresponding with the concentrically laminated body found in similar stages of 
the egg in some spiders ; at the same time, I desire rather to throw this out as a hint 
than to express it as an opinion. 
Acetic acid slightly darkened the yelk, and made the patch almost invisible. 
Polydesmus (Plate XVI. figs. 4, 5, 6, 7). — In form and arrangement the generative 
organs, both male and female, in this genus resemble those of lulus. The development 
