166 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
between 20° and 30° C. Lowered temperature lessens the frequency 
of the beats, and increases the changes in volume, as well as the duration 
of the systole in relation to the diastole. Increased temperature has 
an opposite effect, also in agreement with what is true of Vertebrates. 
The beats ceased about 40° C., and the facts are against the supposition 
that the cessation is due to a coagulation of muscle-plasma, but in 
favour of the supposition that the change in metabolism (e. g. an 
accumulation of katastates) inhibits vitality. No ganglion-cells or 
nerve-fibres were visible in sections of the hearts of Salpa , Ciona, 
or PterotracJiea. 
Blood-corpuscles of Invertebrates.* — Dr. Ph. Knoll lias studied these 
in Lamellibranchs ( Pectunculus , Area , Solen, Unio , &c.) ; Polycheeta 
( Notomastus , Dasybranchus , and others) ; Echinoderma ( Cucumaria , 
Strongylocentrotus ; Tunicata (Ciona, Styela , Phallusia, &c.) ; Cephalopoda 
(Sepia, Eledone , Octopus ) ; Gastropoda (Murex, Dolium, Aplysia , &c.) ; 
Thoracostraca ( Astacus , Homarus, Squilla, Palinurus, Pagurus, &c.). 
The corpuscles are all demonstrably nucleated, except in a few 
cases, where the granulations probably hide the nucleus. But the size 
of the nucleus in relation to the cytoplasm varies widely in the same 
order, or even in the same individual. In Tunicates the nucleus appears 
disproportionately small. 
The typical structure of the nucleus is a reticulum with thickenings 
at the nodes. All signs of division, whether of coloured or colourless 
corpuscles, were amitotic. 
Knoll discusses the various granules contained in the corpuscles, 
many of which seem to be signs of active assimilative processes, while 
others, e. g. in the leucocytes of Notomastus , appear to be excretory ; 
the changes of shape in coloured as well as colourless corpuscles ; and 
the probability that amitotic multiplication occurs in part in the fluid 
blood. 
Mollusca. 
y. Gastropoda. 
Anatomy of Mollusca.j — Dr. L. Plate has found on the coast of 
Chili a number of Phidiana inca , and has taken the opportunity of making 
careful dissections of it. He has further some notes on the anatomy of 
Siphonaria concinna, the renal organ of which was found to consist of a 
ventral and a dorsal lobe. The former lies in the floor of the mantle- 
cavity, and is smaller than the latter. The dorsal lobe opens near the 
respiratory cleft by a small papilla. The organ is sj)ongy in texture, 
and has no special ureter. 
Subtropical Miocene Fauna in Arctic Siberia.^ — Mr. W. H. Dali 
has examined a small collection of fossils, comprising six species of 
Mollusca brought in 1855 from the Gulf of Penjinsk. The evidence 
afforded by them indicates unmistakably that the fauna included species 
that must have flourished in waters at least as warm as those now found 
in the Sea of Japan, or at a distance more than a thousand miles to the 
southward. The species themselves point to a distinct analogy with 
those of the seas of China and South Japan, and like the existing fauna 
* SB. K. Akad. Wiss. Wien, cii. (1893) pp. 440-78 (2 pis.), 
f SB. Akad. Wiss. Berlin, 1891, pp. 219-24. 
X Proc. U.S.'Nat. Mus., xvi. (1894) pp. 471-8 (1 pi.). 
