ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
769 
Movement of Diatoms.* — Prof. 0. Butschli lias observed the follow- 
ing phenomenon in Pinnularia nobilis, with the aid of an infusion of 
Indian ink in the water. At the point of the raphe which adjoins the 
central node of each valve, the fine granules of Indian ink collect in 
larger or smaller masses, apparently connected with the raphe by a 
viscous binding substance. After some time a very delicate filament 
was often seen to shoot out from the lump and to elongate itself along 
the raphe, though it was not in direct contact with it, but formed an 
acute angle with the surface of the diatom. The end of this filament is 
sometimes swollen in a club-shaped manner. The filament is absolutely 
colourless and transparent, and has very nearly the same index of 
refraction as the water. It is not stained by anilin-dyes, and is only 
rendered visible by the particles of Indian ink adhering to it. The 
elongation of the filament takes place by jerks, and this is apparently 
the cause of the jerking motion of diatoms, the frond being pushed back 
by the lengthening filament, the distal end of which rests on the sub- 
stratum. When the diatom lies on its girdle-side, two of these filaments 
may be seen, one on each side, directed usually towards the same end of tho 
diatom, occasionally towards opposite ends. Experiments with other spe- 
cies of diatoms gave negative results. According to this explanation the 
movement of diatoms presents considerable analogy to that of desmids. 
Microcrocis, a new Genus of Cyanophycese.j — Under the name 
Microcrocis Dieteli , Herr P. Richter describes the type of a new genus 
of Cyanophyceae, with the following diagnosis : — Thallus parvulus, 
oculis nudis visibilis, serugineo-viridis, siccitate violascens, membranaceo- 
subfoliaceus, libere natans, e cellularum strato unico formatus ; cellules 
geminee, pseudoparenchymatice conjunctae, utroque polo rotundatae, 
planitiem versus perpendiculariter positas, e vertice sphaericas, tegumento 
universali circumdatas ; divisio cellularum in planitiei utramque directio- 
nem, ut in Merismopedio. Microcrocis is nearly allied to Merismopedium. 
Prof. G. v. Lagerheim | identifies M. Dietelii with his own Merismo- 
pedium ( Holopedium ) geminatum. He now proposes Holopedium as an 
independent genus, with the following diagnosis : — Familiis forma irre- 
gulari e cellulis irregulariter dispositis compositis ; divisio cellularum 
irregularis. It is distinguished from Merismopedium by its irregular, as 
contrasted with a rectilinear mode of cell-division. 
To this Herr Richter § replies, maintaining the essential distinction 
of Microcrocis and Merismopedium. 
p. Schizomycetes. 
Bactericidal Action of a Continuous Electric Current. || — Drs. E. 
Burci and Y. Frascani have made the following series of experiments. 
First, they tested the effect of nascent iodine obtained by electrolytic 
action from a solution of potassium iodide. The result was the destruc- 
tion of the spores ( Staphylococcus pyogenes aureus , Streptococcus , Bacillus 
urese, &c.). Secondly, they applied the electric current directly to 
tissues affected by erysipelas. The effect was a slight retardation and 
* Abhandl. naturh.-med. Ver. Heidelberg, iv. (1892) pp. 580-6 (1 fig.). 
t Richter’s Phycotlieca universalis, Fasc. xi. (1 fig.). See Hedwigia, xxxii. 
(1893) p. 74. 
t La Nuova Notarisia, iv. (1893) pp. 207-10 § Tom. cit., pp. 292-8. 
|| Atti Soc. Tosc. Sci. Nat. Pisa, xii. (1893) pp. 99-119. 
