52 SUMMARY OF CURRENT RESEARCHES RELATING TO 



current produced quietness or, at a maximum, paralysis. Herr Hermann 

 does not yet attempt to draw any general conclusion from liis results. He 

 notes in a postscript the clear and almost transparent appearance of the 

 larvae after even a short darkness, and further the presence of air in the 

 rudimentary lungs, while the alimentary tube never contained any. 



B. INVERTEBRATA* 



Minimum Temperature consistent with Life-f— lu a series of experi- 

 ments on about two dozen worms, Arthropods, and Molluscs, Dr. H. Roedel 

 has extended Pouchet's well-known researches as to the resistance of 

 animals to cold. His general results are as follows : — 



1. Lower animals become frozen at temperatures varying greatly in the 

 different genera and species. The resistance varies with the actual body- 

 heat of the animal, with its size, structure, and protective covering, with the 

 freezing-point of the blood, &c. 



2. The resistance usually increases with progressive development, but 

 sometimes the adults are more sensitive than the young. 



3. Nothing can be directly inferred from the geographical distribution. 



4. Perfectly frozen animals are never revivified. 



He proposes a curve with the degree and the duration of the temperature 

 as co-ordinates. These two factors must be considered together. The 

 absolute minimum is obviously the fatal temperature in unit time. He 

 enumerates the various results as exhibited by degeneration, cessation of 

 certain fimctions, sleep-like paralysis, and death ; and sums up his experi- 

 ments in a tabular survey. 



New Function for Invertebrate Otocysts.J — M. Y. Delage has made 

 a series of experiments on Sepia and some Crustacea (Mysis, Palsemon, and 

 Polyhius), in order to ascertain the effect produced on their powers of 

 swimming by the removal of the eyes and otocysts. 



He finds that the removal of the eye does not inconvenience the 

 animal to any great extent ; it will continue to swim in the ordinary 

 way, but rather more slowly ; it does not turn over on its dorsal surface, 

 and keeps straight on its course. But on the removal of the otocyst, either 

 with or without the eye, its course is no longer direct, but the animal turns 

 on its axis, performs somersaults, and in fact completely loses control of its 

 actions. 



The author therefore concludes that the presence of otocysts, hitherto 

 regarded only as auditory organs, is necessary for regulating the animal's 

 locomotion. He points out the resemblance between hig own results and 

 those of Fleurens on rabbits and pigeons. 



Function of the Malpighian Tubes of Insects and Nephridium of 

 Pulmonate Mollusca.§ — Dr. C. A. MacMunn has obtained uric acid 

 crystals from these organs, establishing that the view held that they 

 function like the kidney of vertebrates is well founded. 



Pelagic Microzoa of the Baltic. |1 — Dr. 0. E. Imhof, from observations 

 made at four stations in the Baltic, is able to confirm the view of Pouchet 

 and de Guerne as to the connection between the pelagic fauna of the 



* When a paper deals with the subjects of more than cne of the following divisions 

 it is placed here. 



t Zeitschr. f. Naturwiss., lix. (1886) pp. 183-214. 



: Comptes Reiidus, ciu. (1886) pp. 798-800. 



§ Jouru. of Physiol., vii. (188G) pp. 128-9. See extended notice, m/m. Microscopy /8. 



U Zool. Anzeig., ix. (1880) pp. 612- .5. 



