198 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
stomina, and have, consequently, well-developed and long vasa deferentia, 
which are wanting in the other group. The species of Cylindrostoma 
described are C. quadrioculatum and C. Klostermanni. 
Tnrbellaria of the Coasts of France.* — In the present memoir 
Dr. L. Joubin confines himself to an account of French Nemertinea ; his 
chief object is to give an “ apercu ” of the fauna and he notes as much 
as possible the habitat of the worms and the external details which 
are often so difficult to see. Thirteen species were found to be peculiar 
to the Atlantic, seventeen to the Mediterranean, and twenty-eight were 
common to the two areas. Carinella banyulensis sp. n. was first thought to 
be the young of C. annulata , but its maturity was proved by its being 
discovered reproducing itself; C. aragoi is a new species also from 
Banyuls. In describing Polia curta the author, which he rarely does, 
enters into some anatomical details. The new genus Poliopsis is sug- 
gested for P. lacazei sp. n., but the author does not distinguish between 
what he regards as the generic and what as the specific characters. The 
names marionis and rustica are applied to new species of Tetrastemma. 
The only new species of Nemertes is N. duoni. 
Asexual Reproduction of Microstoma.! — Dr. F. von Wagner has 
made a study of the asexual reproduction of this worm. He is not able 
to confirm v. GratFs statement that the length of proliferating specimens 
is from 0*7 to 1*5 mm., as he has observed examples 2 mm. long in 
which there was no indication of the reproductive process. The law of 
Hallez that rudiments of new zooids always appear in the last third or 
fourth is not universally true. There are great variations in the rhythm 
of asexual propagation, and v. Graff s formula is rather a theoretical 
generalization from special cases than the result of comparative observa- 
tion. Hallez’s “ temps de formation ” does not so much fix a definite 
developmental stage of the developing zooid as represent a special stage 
of the mother; the isolated hinder piece is not a localized growth- 
product of the animal which is known as the mother, but is merely a 
part of it ; the constancy in size of the most anterior animal of a chain, 
which v. Graff supposes to continue for the whole period of asexual 
propagation, does not really obtain. The internal processes which 
accompany asexual reproduction may be considered under two heads : — 
A. Formation of septa and separation. — The enteric tract becomes 
constricted in the septal plane, and is, consequently, in a state of latent 
tension of high degree ; the process of separation happens at a period 
characterized by the growth-energy of the epithelial circular groove 
having reached a stage in which it is superior to the tension of the 
constricted enteron. 
B. The processes of regeneration are discussed in eight brief chapters 
they chiefly consist of changes in and differentiations of the formative 
cells belonging to the parenchyma. If what happens in Microstoma is 
compared with what is known to occur in other Turbellaria, we are led 
to the generalization that in the Turbellaria regenerations take their 
origin from the parenchyma (mesoderm) ; in other words, the regene- 
