DEVELOPMENT OF CIBBIPEDIA. 
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development, as are also those contained in the lamellae. In Balanus the ramified caeca 
of the ovarium show ova in different stages of development. According to Buchholz *, 
who saw the youngest ova in the caeca, and describes them as transparent small vesicles 
with a germinal vesicle and a nucleolus (exactly the same as may be seen in the tubes 
of Le'pas fascicularis ), these vesicles grow as well as the ova — a statement which, I 
think, may also be made for the latter. As these vesicles grow they are more and 
more filled with yelk-granules, until the vesicle is no longer visible and only the nucleolus 
is seen as a clear spot in the centre of the ovum (Plate 10. fig. 3 and fig. 1 ,n). 
Evidently the shell round these ova is not yet formed, as they are soft and change their 
form according to their position in the ovary. Among these large developing ova you 
may see in this stage small transparent cells, with a vesicle and a nucleolus (fig. 3, oi ), 
which do not take up any yelk-granules, and which are, I think, the mother cells 
from which the next set of ova will be derived as soon as this one has advanced into 
the ovarian lamella. I looked of course for such cells as have been described in 
Sacculina by Van Bexeden f, but never saw any of them budding ; nor did I ever see 
those “ cellules accolees” on one of the poles of the growing ovarian cell which he has 
described. They must be peculiar to the latter genus, where they have been seen by 
Gerbe as well as by Vax Bexedex, while in Balanus Buchholz seems not to have 
remarked any thing of the kind. 
In our species I think the small cells divide by budding, and give rise to more small 
ova, which have the same form as the mother cells, and afterwards grow in the way 
which has been described above. 
The spermatozoa are hair-like filaments, which offer no special character (fig. 3, a). 
I have, however, not studied their development. 
After the last-described stage (Plate 10. fig. 1, n, and fig. 3) the ova leave the ovarium 
and get into the ovarian lamellae, which may be easily found on both sides of the body. 
How they get there has been a subject of much speculation. Krohx’s theory of 
Darwix’s auditorial sac being the orifice through which they have to pass, seems to 
me to be the most likely one ; but only carefully done sections of mature specimens 
will be able, I think, to solve this question, which is not an object of the present 
inquiry. The ova, as we find them in the lamellae, are ellipsoidal. They have acquired 
a shell during their passage through the oviducts, and show no trace of the nucleolus 
vesiculae germinalis. They have in this stage a length of 0-26 millim. 
Burmeister thinks that each of the lamellae contains about 2000 ova. He also 
figures some ova, which, judging from their shape, are later stages in which the 
embryo begins to be visible within. The mature ovum is entirely filled with granular 
* J. Mtoter imd It. Buchhoiz, “ TJeber Balanus improvisus , Darw., var. grypliicus , Miitr.” Berlin, 1869. 
An abstract is given in Greka cher’s Beport for 1869 in Henle and Meisner’s 4 Berieht,’ &c. (Leipzig, 1871), 
p. 424. 
t “ Beeherches sur l’embryogenie des Crustaces. III. Developpement de l’cenf et de l’embryon des Saceu- 
lines,” Bull, de l’Acad. Boy. de Belgique, 1870. 
T 2 
