198 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
is entirely wanting in tlie former ; (y) G. holothurise is contained in 
stalked vesicles, which are formed by evagination of the blood-vessel 
long before encystment, and breaks loose into the body-cavity to sporu- 
late, while G. irregularis appears not to evaginate the wall of the blood- 
vessel until it is ready to encyst, and to sporulate in the vesicle. 
Mr. Minchin discusses the attempts that have been made to precisely 
locate these species, and comes to the conclusion that it is at present best 
to leave them in the old genus Monocystis , and to wait for further 
researches to determine their true affinities. It is not until the Gre- 
garines of many Holothurians have been thoroughly worked out and 
compared, that we can be sure what characters are constant peculiarities, 
and what are merely characters of adaptation. He thinks it is highly 
probable that the different species of Holothurians will prove to have 
closely allied species, derived from a common ancestor which inhabited 
the ancestors of the genus Holothuria. 
He justly remarks that the present custom of opening “ any animal 
that comes to hand ” and at once describing “ the Gregarine that inevit- 
ably occurs in it as a new genus and species ” is not the way to advance 
our knowledge of the group. 
Life-history of Gregarina.* — Mr. W. S. Marshall has studied Grega- 
rina ( Clepsidrina ) blattarum v. Sieb. He divides the life-history into 
three stages : — (1) from the development of the nucleoli, and the origin 
of the spores (i.e. the bodies within which the spindle-shaped young 
Gregarines arise) to the formation of the “blastoderm-stage ” ; (2) the 
migration of the spores towards the centre, and the formation of eight 
chromatin bodies; (3) the development of the spindle-shaped young 
Gregarines. Mr. Marshall has also some observations on the cuticle 
and the longitudinal fibrils. He believes that what has been repeatedly 
described as a second nucleus is not really such. A new species of 
Didymopliyes — D. Leuckarti , from species of Aphodius , is described. 
Myxosporidia of Gall-bladder of Fishes.f — M. P. Tlielohan, who 
has lately described in the 4 Bulletin de la Societe Philomathique’ for 
1892, an interesting species of Myxosporidia, which he calls Ceratomyxa 
sphserulosa , from the gall-bladder of Galeris canis and of Mustelus Isevis , 
now describes some other new species of the same genus. C. agilis has 
been found in Trygon vulgaris ; in it the pseudopodia are always placed 
near the anterior end, in the neighbourhood of which there is constantly 
a mass of fatty globules. C. appendiculata is the name given to the 
parasite of Lophius piscatorius ; it contains protoplasmic masses which 
are remarkable for the existence of long immobile prolongations, 
formed of an endoplasmic axis which is covered by exoplasm. 
In a second communication | M. Thelohan describes C. arcuata 
from the gall-bladder of Motella tricirrata ; this species is somewhat 
smaller than the preceding, being not more than 35 or 40 /x in diameter, 
and the spores are relatively very small. Another form, which, at 
Roscoff, is very common in M. tricirrata and M. maculata, becomes the 
type of a new genus which is to be called Sphseromyxa ( S . Balbianii 
sp. n.) ; an incomplete notice is given of its generic characters, but 
* Arch. f. Naturg., lix. (1893) pp. 25-44 (1 pi.). 
f Comptes Rendus, cxv. (1892) pp. 961-4. 
x Tom. cit., pp. 1091-4. 
