ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
607 
according to Lauterborn, purely hypothetical. The production of 
motility by streaming protoplasm would be an isolated phenomenon 
either in the vegetable or the animal kingdom ; while movements caused 
by the excretion of mucilage occur also in the Desmidiese and 
Oscillatorieae ; and, according to Schewiakoff, also in the creeping 
Gregarinidse. 
Herr O. Muller * * * § replies to the objections of Lauterborn to his hypo- 
thesis that the movements of diatoms are effected by means of a proto- 
plasmic thread extruded from the raphe, and adduces fresh arguments 
in its favour derived from the observation of the same three species of 
Pinnularia. The viscid substance of this thread he states to be distinct 
from the non-viscid substance of the mucilaginous layer, and identical 
with the layer which flows in the immediate proximity of the raphe. 
The analogy sought to be drawn between the nature of the movements 
of diatoms and of desmids is a deceptive one. It is true that the 
protoplasm, in its escape, excretes mucilage also ; but this hinders, 
rather than promotes, the movement of the diatom. 
£. Schizomycetes. 
Effect of Sunlight on the Human 'Organism and on Micro- 
organisms.! — Dr. H. Schickhardt finds that sunlight exerts an un- 
favourable influence on most micro-organisms, either by interfering with 
their development or by completely destroying them. The time required 
for destroying them varies according to the nature of the individual 
bacteria and their pabulum, and depends on the intensity of the light 
and the length of its action. The effective agent appears to lie in the 
chemical rays (violet and ultra-violet). While light has a direct 
bactericidal action, it also exerts some influence on the nutrient medium ; 
at any rate this is demonstrable when the bacillus of typhoid is grown 
on gelatin. On mould-fungi sunlight has no influence. 
Action of Nuclein Acid on Bacteria.^ — Dr. H. Kossel finds that 
nuclein acid which was obtained from lymph cells of the calf possesses 
powerful bactericidal properties. A 0 * 5 per cent, solution kills cholera 
vibrios in 3-5 minutes, typhoid bacilli in 1-1^ hours, streptococci in 
about 2 hours, staphylococci in 6 hours, while anthrax spores take 24 
hours. The author assumes that the bactericidal power is the result 
of the precipitation of albumen by the acid. 
Formation of Sulphuretted Hydrogen and Mercaptan by Aerobic 
Bacteria. § — Drs. E. J. Petri and A. Maassen find that anthrax, Tetra- 
genus, diphtheria, hay bacillus, root bacillus, and potato bacillus do 
produce H 2 S, and that the formation of this gas is influenced by the 
presence of various agents or is even concealed by them. Thus with all 
bacteria the H 2 S production, even in the presence of free sulphur, is 
* Tom. cit., pp. 136-43 (1 fig.). 
t Friedreich’s Blatter f. Gerichtliche Medizin u. Sanitats-polizei, xliv. (1893) 
pp. 350-92, 400-38. See Centralbl. f. Bakteriol. u. Parasitenk., xv. (1894) p. 1020. 
X SB. Phys. Gesellsch. zu Berlin, Dec. 8, 1893. See Centralbl. f. Bakteriol. u. 
Parasitenk., xv. (1894) p. 1018. 
§ Arb. a. d. Kaiserl. Gesundheitsamte, ix. (1893) pp. 490-506. See Centralbl. f. 
Bakteriol. u. Parasitenk., xv. (1894) pp. 908-9. 
2 T 2 
