78 SUMMARY OF CURRENT RESEARCHES RELATING TO 
the “ brain.” The original ventral nerve-eord remains functional and 
complete until the separation of the zooids occurs ; it increases partly by 
the proliferation of its own cells, partly by the intervention of the 
ectodermic cells. The fore-gut originates as an endodermal outgrowth 
of the gut, at first unpaired and later paired ; the two branches fuse 
with two very small ectodermic invaginations, and form ultimately the 
unpaired mouth and gullet. The mid-gut increases by the proliferation 
of its own cells, the hind-gut by the fusion of the torn edge of the mid- 
gut with the body- wall. The origin of the other organs was not 
certainly ascertained. 
The author compares these results with those of others, and points 
out the following peculiarities : — The endodermal origin of proctodaeum 
and stomodaeum, the originally paired condition of the mouth (already 
described in some other cases), the fact that the supra-oesophageal 
ganglia are formed from ventral and not from dorsal cells. These 
peculiarities he explains on mechanical grounds, and, in an interesting 
discussion of the germ-layer theory, maintains that they show that in 
regenerative processes the organism “ enjoys great freedom, and accom- 
plishes these in the way which the physiological, or even the mechanical, 
conditions, render most suitable.” He does not believe that nature can 
be confined in a scheme in the fashion suggested by the germ-layer 
theory. 
In the course of some observations on asexual reproduction, the 
author emphasises his belief in the essential similarity of division and 
budding. 
Branching Annelid.* — M. Caullery and F. Mesnil describe an 
interesting abnormality in Dodecaceria conchanim Oerst., in which it 
seems as if a fragment of four segments had bifurcated anteriorly and 
had also given off a posterior branch — a case of regeneration with 
heteromorphosis. 
New Species of Clymene.f — Miss M. Lewis describes Chjmene jpro- 
ducta sp. n., one of the Maldanidse, but with a much larger number of 
segments than any known form. It constructs a tube of coarse sand, 
similar to that of Axiothea torquata , with which it was found associated 
on the sand flats of Vineyard Sound, Mass. There seem to be about 
seventy segments, — four to the thorax, five to the abdomen, and about 
sixty to the tail. The external characters are fully described. 
Acanthobdella peledina.J — Prof. A. Kowalevsky amplifies his pre- 
vious description of this interesting animal, which occurs in Lake Onega 
as an ecto-parasite on Salmo salvelinus, and probably also on Salmo trutta 
and Coregonus albula. 
He describes small reserve setae at the base of the large setae, three * 
pairs of eyes resembling those of Piscicola , the pigment-cells, the parti- 
tions separating the somites, the lateral lines, the ventral and dorsal 
blood-vessels, the food-canal, which in many ways recalls that of Oligo- 
chaeta, the ventral chain of (20) ganglia, of which the sub-oesophageal 
and the most posterior show distinct traces of being composed of several 
* Zool. Anzeig., xx. (1897) pp. 438-10 (3 figs.). 
f Proc. Boston Soc. Nat. Hist., xxviii. (1897) pp. 111-5 (2 pis.). 
X Bull. Acad. Sci. St. Petersbourg, v. (1896) pp. 263-74 (7 figs.). 
