SUMMARY OF CURRENT RESEARCHES RELATING TO 
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Disruption Products of Nuclein Acid.* * * § — Herren A. Kossel and A. 
Neumann begin by explaining wby it is that we kuow so little in regard 
to sucli substances as nuclein acid. But that is the chemist’s affair. 
Ours is that nuclein acid occurs, by itself or in association with albumen, 
in the nuclei of all living cells. Subjected to boiling water or boiling 
dilute mineral acids it gives rise to the so-called nuclein bases — adenin, 
hypoxantliiu, guanin, xanthin. The authors have concentrated their 
attention on that particular form of nuclein acid which yields only 
adenin. From this they derive first “ paranuclein acid,” then “ thymin 
acid,” and finally a crystallizable substance “thvmin” whose composi- 
tion corresponds to the formula C 23 H 26 NgO (! . This was got from the 
thymus gland and also from the spleen. From this thymin they then 
derived levulin acid, a carbohydrate. This discovery brings the chemist 
a step nearer knowing the constitution of nuclein acids. It also adds 
another to the possible sources of carbohydrates in the body. 
Distribution of Lacustrine Plankton.! — Dr. 0. Zacharias has con- 
vinced himself as to the erroneousness of the frequently accepted 
conclusion that there is uniformity of distribution in the plankton of a 
lake-basin. He gives facts showing that swarms may be local and that 
certain forms have their favourite haunts. A few sample hauls are apt 
to lead to partial conclusions ; vertical hauls must be corrected by 
horizontal hauls ; and quantitative plankton studies must be associated 
with qualitative investigation. 
B. INVEETEBEATA. 
False Mimicry.^ — Prof. F. Plateau points out that true mimicry 
must be between animals living in the same district, under similar con- 
ditions, and occurring together at the same time of year, and that 
the mimicked form must possess means of defence which the mimicking 
form lacks. But there are cases of resemblance between different 
animals, in which the above conditions of true mimicry are not fulfilled. 
These are cases of “ false mimicry,” fortuitous resemblances due to the 
fact that the possible combinations of colours and shapes are not un- 
limited, and are therefore likely to repeat themselves. 
He instances the Medusoid-like Amphipod ( Mimonectes ) described by 
Bovallius, the spider Formicina lanestrina which is ant-like, but is not 
found near ants, the two nocturnal Lepidoptera Diclionia aprilina L. and 
Moma Orion Esp., which are like one another, but appear at different 
seasons, the Argentine Phyciodes and the Old World Vanessa , the 
African Cochlophora valcata whose larval state is like the Gastropod 
Valvata along with which it does not occur. 
Terrestrial Fauna of Damma Island, East Indian Archipelago.§ — 
Mr. J. J. Walker, R.N., who visited this island during the voyage of 
H.M.S. ‘ Penguin,’ writes a general introduction to a series of reports 
by a number of specialists. More than 180 species of terrestrial and 
freshwater forms were collected in five days, and were of considerable 
* SB. K. Preuss. Akad. Wiss., 1894, pp. 321-7. 
t Biol. Centralbl., xiv. (1894) pp. 122-8 ; Forschungsberichte Biol. Stat. Plon, 
ii. (1894). % Bi°h Centralbl., xiv. (1894) pp. 471-3. 
§ Ann. and Mag. Nat. Hist., xiv. (1894) pp. 49-71, 98-110. 
