ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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by the delicate funnel-shaped collar. These collars have extremely fine 
outlines, but all are connected at their margins by a very distinct 
membrane (Sollas’ membrane). Neither Prof. Sollas nor Mr. Dendy 
have till now been able to see flagella in concrescent choanocytes, but 
Mr. Dendy has now been so fortunate as to see them plainly projecting 
from the bodies of the collared cells ; he has thus decided the question 
of the coexistence of Sollas’ membrane and the flagella of the collared 
cells. Bidder has already forestalled the author in a suggestion he was 
about to make — that this membrane serves to filter food-particles from the 
current of water flowing through the Sponge. 
The ova are remarkable for their great complexity of structure. In 
Grantia labyrinthica the mature ova migrate through the walls of the 
inhalant lacunae and remain suspended therefrom ; each has its distinct 
peduncle and awaits the spermatozoa brought in by a stream of water. 
It is probable, though it has not been proved, that the lacunae of 
H. panicea , in which the ova are found suspended, are also inhalant. 
The adult ovum has a total diameter of about 0*067 mm. The outer- 
most portion forms a distinct envelope, which is fairly thick. Within this 
envelope the ovum proper is suspended as in a bag; it is spherical, 
uniformly and rather coarsely granular ; the spherical nucleus has a 
very thick and distinct membrane, and the substance is finely granular, 
it stains lightly, whereas the substance of the single spherical nucleolus 
stains very deeply. 
Protozoa. 
Stentor caeruleus.* — Dr. A. Schuberg finds much to correct in 
previous descriptions of the structure of Stentor cseruleus. He gives his 
own observations on the superficial stripes, and their “ ramifying zone,” on 
the so-called “ peristome ” and its insunk oral region or “ gullet,” on 
the frontal region, and on the adoral membranellee. In regard to 
the blue pigment, of which so little is known, he tells how some five- 
year-old preparations of this species had acquired the dark purple-red 
colouring of St. igneus, and how three living specimens which he isolated 
lost their pigment entirely and afterwards regained it. Schuberg has 
also discovered some new facts in regard to the process of division, and 
this especially, that the whole constriction is from the first connected 
with a rupture of the pellicle in a definite direction. In discussing the 
comparative morphology of Stentor , he maintains that the so-called 
peristome is not in toto homologous with that of other Infusorians, 
indeed that it is homologous with the “ frontal region ” of the Hypotricha 
and other Heterotricha, and should be renamed as such. 
The Life of Difflugia.j — Dr. M. Verworn has found in Difflugia 
lobostoma an interesting object of study. In the specimens examined, 
the shell had no sand particles, but consisted of irregular plates made 
by the animal itself and of organic debris. It seems that the little 
plates arise from peculiar grains which lie round the nucleus and are 
probably formed as a secretion under nuclear influence. When an 
individual divides, these grains are exposed on the surface of the 
separated cell, unite firmly with one another, and form a connected case 
* Zool. Jahrb., iv. (1890) pp. 197-238 (1 pi.). 
f Zeitschr. f. Wiss. Zool., 1. (1890) pp. 443-68 (1 pi. and 3 figs.). 
