494 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
projection Microscope. The apparatus consisted of an alternating 
current arc-lamp of fifty-two volt twelve ampere capacity. The light 
was taken by a pair of 4J-in. condensers, and was passed through an 
alum cell, a biconvex condensing lens, an Abbe condenser, and finally 
to the objective. When a healthy unstimulated Hydra was placed in 
the field, it underwent violent contraction, discharged its stinging cells, 
and began to lose its ectoderm cells. The whole of the ectoderm was 
lost in a period varying from one to eleven minutes. When the polyps 
were placed in fresh water, they recovered the ectoderm in a period 
varying from nine to thirty-three days. The dropping-off of the ecto- 
derm cells resembled in some ways the blistering effects produced on 
the human skin by the Rontgen rays. These rays are present in small 
quantity in the light from an arc-lamp. 
Species and Environment in Hydroids.* — Herr A. Birula has 
noted some interesting environmental variations in Campanularia. Two 
species, G. Integra MacGillivray and C. caliculata Hincks, were united 
by Levinsen on account of the existence of numerous transitional forms 
between them. Birula finds that the second inhabits shallow water, and 
that its peculiarities seem to have a direct relation to the force of the 
currents. Its calyx is of oval form and thickened at the poles, and 
the colonies grow so that the thickened areas receive the force of the 
current. The typical form, C. Integra , grows in deep water where cur- 
rents are not felt, and has a uniformly rounded thin-walled calyx. 
Somewhat similar conditions exist in Sertularella tricuspidata ; while in 
other cases different species inhabit deep and shallow water. Both 
in the cases of Campanularia Integra and of Sertularella tricuspidata, the 
intermediate depths are occupied by transitional forms. 
New Family of Palceozoic Corals, j — Mr. Amadeus W. Grabau pro- 
poses the new family MoNiLOPORnxas for the two genera Monilopora and 
Ceratopora , each represented by several species, and forming a natural 
association, with features which separate them from other Palaeozoic 
corals. The earlier of the two genera is Ceratopora , and it is less special- 
ised in structure. The diagnosis of the new family is as follows : — 
Compound branching coralla, composed of cylindrical or funnel-shaped 
corallites, which either remain connected by their visceral cavities, or 
become separated within by the disposition of continuous layers of 
sclerenchyma ; tabulae absent ; walls thickened by the addition in- 
ternally of concentric layers of sclerenchyma, which either are closely 
applied or leave variously shaped cavities or lacunae between successive 
layers ; septa absent, or represented by costae and trabeculae ; asexual 
reproduction by basal and lateral gemmation ; range from Devonian to 
Carboniferous. 
Porifera. 
Geographical Distribution of European Spongillidse.^ — Dr. Paul 
Girod takes a survey, and concludes that there are five main European 
forms, namely, those found in France — Spongilla lacustris, Sp. fragilis , 
* Arm. Mus. Zool. St. Petersbourg, 1898, pp. 203-14 (Russian). German abstract 
in Zool. Centralbl., vi. (1899) pp. 518-9. 
t Proc. Boston Soc. Nat. Hist., xxviii. (1899) pp. 409-24. 
i Bull. Soc. Zool. France, xxiv. (1899) pp. 51-3. 
