QUARTERLY CHRONICLE. 45 
is to be placed with abundance of indigo. In this way little 
lagoons are formed, in which the Infusoria become imprisoned, 
and are examined without the use of a glass cover. The 
systole of the vesicle takes place once in forty seconds ; be- 
tween diastole and systole the vesicle is more or less irregu- 
lar in outline, but gradually approximates to a spherical form, 
and the contraction is sudden and rapid. If the water in 
which the specimen is placed be not renewed the systole 
occurs five or six times in a minute, owing to the unhealthy 
condition. Tincture of opium stops the action of the con- 
tractile vesicle at once; the effect is to swell it to an enor- 
mous size, and then, breaking through the posterior end of 
the animal, it expands to a dimension often exceeding that 
of the whole body before it bursts. The mouth, esophagus, 
and digestive vacuoles, are carefully described. It appears 
that the flagellum has nothing to do with the mouth, which 
is entirely dependent on the small cilia surrounding it for 
the introduction of food. The vacuoles are sometimes very 
large, but the particles of food taken in are excessively 
minute. No anus was detected, as, indeed, was not expected. 
The flagellum is composed of several filaments, which fre- 
quently divide into two groups or are spread out at times as. 
a brush. Its function appears to be that of a powerful rud- 
der and axis of gyration. ‘The so-called cuirass is evidently 
a part of the whole investing tunic, but differs from the rest 
in its punctuation. The nucleus in December had a U-shaped 
form, and was of large size. Frequently it was observed to 
be invested by a delicate envelope, and close to its dorsal re- 
gion a vesicular corpuscle, appareutly the nucleolus or testi- 
cule, was observed overlying it. Reproduction from the egg 
was not observed, but transverse division, as observed by 
Allman, occurred in many instances. 
“ On the Microscopic Structure of the Shell of Rhynconella 
Geinitziana” is the title of a paper, by Dr. Carpenter, in the 
November number. It may be remembered that a somewhat 
unequal discussion has been going on between Dr. Carpenter 
and Professor King, of Galway, as to whether, as Dr. Carpenter 
ably maintains, the shell in question and the Rhynconellide 
generally are imperforate in their histological structure, or 
whether, as Professor King asserts, the Rhyncopora Geinitziana 
has a perforated structure similar to that of the Terebratu- 
lide. Dr. Carpenter has re-examined his preparations made 
from specimens supplied by Mr. Davidson, and clearly points 
out the origin of Professor King’s mistake. The internal sur- 
face of the debated shell is pitted. When the outer surface 
is abraded these pits appear as complete perforations ; and a 
