ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
199 
umbrella of a Bhizostomid the fish Caranx auratus was found ; other 
small fishes seek shelter among the extraordinarily long spines of 
Diadema setosum. 
The Plankton Pump.* * * § — Prof. J. Frenzel describes the use (in lakes) 
of the Plankton pump, which has proved itself advantageous on ice- 
eovered waters, and is probably capable of much wider utilisation. For 
slight depths it is both cheap and practicable ; but the cost of the india- 
rubber tube mounts up with every yard, and what the pump can do in 
deep water explorations remains to be seen. So far as it has been used, 
fit compares favourably with even Ilensen’s net. 
Plankton of Faeroe Channel-t — Dr. G. H. Fowler, in the first of a 
series of notes on the Plankton of the Faeroe Channel, describes Sagitta 
Whartoni sp. n., which differs from all other species yet described in 
the approximation, almost fusion, of the paired lateral fins ; Sjpadella 
( Krohnia ) hamata Mobius, of which a better outline figure than has 
hitherto been given is furnished ; and Salpa asymmetrica sp. n., the 
eighteenth now recorded from the N. Atlantic. 
Variation of the Plankton.}: — Dr. J. Hjort has published a very 
interesting memoir describing his hydrographic-biological studies off 
the Norwegian coast. He has much to say in regard to the diversity of 
the Plankton at different seasons. The conditions on w r hich the periodi- 
cally diverse appearance of the Plankton depends are many and various. 
Of greatest importance are (1) the ocean currents and the variations in 
salinity ; (2) the propagating period of the various organisms concerned ; 
and (3) the variations of wind and light. 
Physical Basis of Animal Phosphorescence.! — Mr. S. Watase has pub- 
lished an entertaining lecture on this subject, and promises a monograph. 
In some historical notes he quotes largely from Faraday, who surmised 
the results of later workers, showing that a chemical substance, probably 
a secretion, in the glow-worm and the firefly, shines when exposed to air, 
independently of the insect’s life, though the insect does in some way 
control its luminosity. Mr. Watase clears the ground by insisting on the 
continuity of heat and light phenomena, which differ subjectively rather 
than objectively. Usually the organism produces heat without light, 
the firefly produces light without heat. 
The proximate cause of luminosity in the animal kingdom may be 
due to a variety of secondary circumstances : — (1) there maybe luminous 
bacteria present pathologically ; (2) there may be symbiotic luminous 
bacteria ; (3) the food may be phosphorescent. 
In fireflies, the luminous cells contain granules, secretions of a fatty 
nature, 'which oxidise readily in alkaline media. Phosphorus has nothing 
to do with the phenomenon. The product of cell-metabolism is oxidised in 
situ and independently of the cell-life, by the inspired oxygen. Through 
its respiratory mechanism the insect may and does control the process ; 
but the last step is the oxidation of a dead substance. Watase closes 
* Biol. Centralbl., xvii. (1897) pp. 190-8. 
t Proc. Zool. Soc. London, 1890 (published 1897), part 4, pp. 991-G (1 pi.). 
X Skrift. Yidenskabs. Christiania, 1895, part 1, No. 9 (published 1896), pp. 76 
and 75 (15 maps, &c.). 
§ Wood’s Holl Biological Lectures, 1896, pp. 101-18 (1 fig.). 
