Miscellaneous. 
319 
are composed only of the glandular part, and which consequently have 
no communication with the interior of the cavity of the body ; 
but further back we find two pairs of normally constructed seg¬ 
mental organs opening directly outwards by a pore. Ophelia bicor- 
nis presents a still more striking example. We find here five pairs 
of segmental organs placed on the sides of the nervous chain, fol¬ 
lowed by five other pairs of glandular pouches destitute of any com¬ 
munication with the interior. Lastly, the Sabellce and the Myxicolce 
have only one pair of renal pouches on the sides of the oesophagus, 
and in all the rest of the body each segment has its pair of segmental 
organs of the typical form. It must be added that the histological 
and chemical characters prove that these glandular sacs are really 
urinary organs, and that the segmental organs, sometimos borrow¬ 
ing from them, sometimes not, are perfectly independent parts, 
having no other function than that of collecting the products of 
generation in order to pour them out. 
There is still much uncertainty with regard to the genital glands. 
My observations lead me to assert that in the sedentary annelids 
the ova and spermatozoids never originate either in the Bojanian 
sacs or in the epithelial cells of the peritoneum, nor are they de¬ 
rived from the nuclei surrounding the blood-vessels, nor even from 
the adipose tissue (sexual tissue of Claparede) ; but there exist very 
distinct glands in intimate connexion with the blood-vessels. 
Thus in Arenicola piscatorum, Terebella conchilega, and Ophelia 
bicornis the male or female genital gland is attached to the vessel 
which comes from the central part of the circulatory appa¬ 
ratus and runs to the segmental organs. The position varies in 
each of these genera; but the number is always equal to that of the 
pairs of segmental organs. In the Terebellce nebulosce the genital 
gland is on the median line around the supranervian blood-vessel, 
and only in the thoracic portion. In Chcetopterus pergamentaceus 
the glands are situated in pairs in each segment and on the sides 
of the intestine. In the Sabellce , again, they are placed in pairs in 
each segment, around the inferior lateral vessel. 
These glands, during the period of repose (winter), consist of a 
certain number of small acini, the structure of which presents nothing 
very distinct. Towards the commencement of the spring the glands 
enter into activity, with differences according to the genera. The 
amorphous mass increases; each acinus becomes more and more 
defined ; and in its interior we see small nuclei appear, around which 
a portion of protoplasm soon becomes limited. The ova are soon 
marked out, and at the same time they are displaced by fresh 
quantities of protoplasm developed at the base of the acinus. The 
gland acquires the form of a bunch of grapes ; and the most mature 
ova arrive at the periphery, the youngest remaining at the base. 
The vitellus gradually becomes granular; and the germinal vesicle 
shows itself. Finally the ovum is detached and falls into the cavity 
of the body. 
The same thing is observed in the case of the testes. The sper¬ 
matic mother cells detach themselves from the glands ; then their 
