340 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
not so successful as Lugol’s solution, to which some alcoholic iodine 
solution had been added until it assumed a dark-brown tone. It would 
seem that this stains the flagella, which are not rendered evident by 
Kannenberg’s method. 
Several other cases of monads in pulmonary gangrene have been 
recorded, but there are also instances of their presence in pleural exuda- 
tion unconnected with gangrene of the lung. Too much importance 
must therefore not be assigned to this otherwise interesting occurrence. 
Infusorial Parasite of Freshwater Fish.* — Dr. 0. Zacharias noted 
that in May 1892, fish kept in a large aquarium at Plon were affected 
with an infusorial parasite which on further examination turned out to 
be a species of Ichthyophthirius. 
The epidermis of fish thus affected seemed, when looked at with a 
hand-lens, as if it were stippled all over with little white prominences. 
On every fish there were several hundreds of these tiny receivers, the 
result of cell-proliferation, and in each was located a large infusorium 
which often exhibited lively movements. 
When viewed from above the parasite is of oval form (0*65-0*8 
mm. long and 0*5-0*55 mm. broad). The upper surface is slightly 
arched and the lower quite flat. The whole surface is covered with 
cilia, and towards the front end is a large horse-shoe-shaped nucleus. 
With reflected light the animalcule is chalky white, with transmitted 
greyish yellow. Within its substance are numerous refracting granules 
and small crystals ; the endoplasma is vacuolar in structure and 
contains numerous tiny hollows, but no contractile vesicle was observed. 
Towards the front of the ventral surface a depression (0*035 mm. deep) 
was noticed, but this was regarded rather as an organ of adhesion than 
as an oral aperture. On this account the author calls the parasite 
Ichthyophthirius cryptostomus. 
The propagation of the parasite is effected in the simplest manner. 
It assumes a spherical shape and invests itself with a very delicate 
sheath, within which cyst it divides into two moieties and from 
each of these two others are produced ; so that in a few hours, from 
one mother-individual 100-150 offspring are produced. These are 
spherical, with a diameter of 0*075 mm. In a comparatively short time 
the cyst is ruptured from the lively movements of the youthful parasites, 
which swim about to find themselves another resting-place on the back 
of a fish. In each young parasite, beside the macronucleus is a micro- 
nucleus, which latter disappears when the animal is a few hours old. 
The parasite is very detrimental to the skin of the fish. This where 
affected is throwm off and thus becomes a ground for the settlement of 
all sorts of vegetable parasites, -e. g. Saprolegnia ferox. 
New Argentine Protozoa. | — Prof. J. Frenzel continues his descrip- 
tion of new forms : — Nuclearina Leuckarti g. et sp. n., with one nucleus, 
one vacuole, rays which are never branched, and no gelatinous envelope ; 
Nuclearella variabilis g. et sp. n., somewhat like Nuclearia Cienkowsky, 
but with one nucleus, and a sharp limitation of the membrane-like ectosarc 
from the endosarc ; Elseorhanis arenosa sp. n. ; Lithosphserella compact a 
* Centralbl. f. Bakteriol. u. Parasitenk., xii. (1892) pp. 718-20. 
t Bibliotheca Zool. (Leuckart and Chun), Heft xii. (1892) pp. 51-81 (2 pis.). 
