470 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
this generally contains one, but sometimes two spherical nuclei. Other 
cellular elements appear to have other functions than that of forming 
the papilla. 
Staining shows that there are three or four nuclei in the centre of 
the papilla ; these are ovoid in form, and belong to fusiform cells which 
are arranged in bundles and traverse the papilla longitudinally. 
The annular pad represents a region in which the sensory elements 
of the papilla are grouped into a larger organ and one of different 
morphological appearance. It is entirely formed of sensory fusiform 
cells, intermixed with which are a few cylindrical elements, and it is 
situated in a zone where the epidermic cells are ciliated. We need not 
wonder at the delicate tactile powers of the proboscis of these worms. 
Nephridium of Lumbricns and its Blood-supply.* — Dr. W.B.Benham 
finds that where Goehlich’s recent statements as to the structure of the 
nephridium differ from those of Gegenbaur, the latter author is the 
more correct. 
He describes in detail the structure of the various regions of the 
nephridial tube, and makes suggestions as to the functions of the parts. 
A comparison is then instituted with the same organ in other genera of 
earthworms; greatest variety in structure obtains in the funnel. It 
has long been known that the nephridium is provided with an elaborate 
blood-supply, but no drawings or detailed descriptions have as yet been 
given ; this lacuna the author now supplies. 
In conclusion, an account is given of the nephridium of Arenicola, 
which has an elaborate vascular network, and a wide intercellular lumen. 
A figure of the whole organ is given, which represents more clearly than 
the generally accurate figures of Cosmovici and of Cunningham the form 
and situations of the parts. 
Regeneration of Tail in Lumbricns.t — Miss H. Randolph has been 
led to conclusions which differ materially from those at present accepted. 
She finds that the new ectoderm arises by the proliferation of the ecto- 
derm around the line of fission. From the ectoderm the ventral nerve- 
chain and the lateral nerve-line are formed. Between these two are two 
other “ foundations ” on each side, which correspond in position to those 
subsequently occupied by the nephridia and the ventral setae. The 
new endoderm is formed from the old ; as the ectoderm grows faster than 
the endoderm the material necessary for the proctodaeal invagination 
becomes formed. The new mesoderm is largely formed from specialized 
cells of the peritoneal epithelium of the ventral longitudinal muscles, on 
each side of the ventral cords ; these cells, which it is proposed to call 
neoblasts, are distinguishable from the cells of the peritoneum by their 
great size and by the presence of a cell-body. They represent the 
“chorda-cells” described by Semper in the Naids and Chsetogaslcr. In 
very early stages, as soon as the ectoderm and endoderm have extended 
themselves sufficiently to form a new cavity, small cells are seen dorsally, 
laterally, and ventrally ; they seem to have no connection with the 
neoblasts and their products, but no positive account can be given of their 
origin. These smaller mesoderm cells give rise to all the circular 
* Quart. Journ. Micr. Sci., xxxii. (1891) pp. 293-334 (3 pis.), 
t Zool. Anzeig., xiv. (1891) pp. 151-6. 
