DEVELOPMENT OF AOANTHODRILUS MULTIPORUS. 515 
pressed a layer of-small darkly staining bodies, the nucleoli, 
which are thus arranged in a peripheral layer, and are not 
found in the interior of the nucleus. 
The presence of four gonads in the embryo is interesting, 
inasmuch as one genus of Oligocheta has always two pairs of 
testes and two pairs of ovaries. I refer to Phreoryctes, 
where the gonads occupy the same segments as in the embryo 
Acanthodrilus. The presence of two pairs of egg-sacs in 
Pericheta aspergillum and other species is evidence in 
favour of the original presence in that worm also of two pairs 
of ovaries; and I have elsewhere sought to show that in 
Kudrilus there are also two pairs of ovaries corresponding to 
the two pairs of testes. In Lumbriculus it is possible that 
the same thing occurs, but the genitalia of this worm have 
not as yet been thoroughly described, though Professor Vej- 
dovsky has promised us an account of them. 
The gonads appear at a comparatively early stage in the 
development of the worm. I first observed them in stage C, 
but as they are in this stage of, comparatively speaking, large 
size, they must be apparent even earlier. I could not, how- 
ever, detect them in stage B. It should be remarked, how- 
ever, that this stage is evidently separated by a considerable 
gap from stage C, and I have nothing intermediate between 
the two. 
In stage C the gonad (fig. 12) is placed close to one of the 
nephridial funnels in which the lumen still persists, and to a 
certain extent the cilia also; but the duct immediately con- 
nected with the funnel has lost the lumen which it possessed 
in stage B, and has become solid. The gonad is in each case 
situated ventrally to the funnel. It is formed by a rounded 
elevation of cells which closely resemble the peritoneal cells 
covering the septum. I cannot say anything about the con- 
dition of the cells forming the gonads, as the histological 
details were not very clear: this was due to the preservation of 
the specimen in saturated solution of picric acid, which does 
not appear to be a good reagent for the preservation of these 
embryos. It is almost unnecessary to say that the four 
