ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
663 
living plant. He dissents also from the statement of Palla,* * * § that the 
bodies which are coloured red by heematoxylin are not found in the central 
body. The author was able to extract the colouring matter of Chroma- 
tium and Oscillatoria in the form of serpentine threads or small lumps, 
by digesting in artificial digestive fluid. 
The author’s views as to the chemical constitution of the dark 
granules found in the sulphur-bacteria were fully confirmed. 
Notwithstanding the absence of a nucleole, the author regards the 
central body of the Cyanophyceae and of the larger bacteria as the 
origin from which has sprung the more complicated true cell-nucleus of 
the higher plants. 
In only a few of the smaller bacteria could a differentiation into 
central body and outer layer be detected. In Spirillum undula the 
polar portions were less strongly stained than the rest of the cell-contents; 
the former correspond to the outer layer, the latter to the central 
portion, in the Cyanophycem and larger bacteria. 
B. Schizomycetes. 
Penetrability of the Intestinal Wall to Bacteria.f — According to 
Herr M. Neisser, who has recently made experiments relative to the passage 
of bacteria through the walls of the intestines, normal chyle is free from 
bacteria and devoid of bactericidal properties; the normal intestine 
consequently does not permit the passage of corpuscular elements. Just 
as little can bacteria be found in healthy lymph-glands or in the blood 
circulation. 
The author then deals with the question whether saprophytic bacteria 
under pathological conditions, or pathogenic germs under normal circum - 
stances, can pass through the intestinal wall. A generally valid rule 
can hardly be made ; for while there are bacteria which, if they emigrate 
from the intestine, are capable of exciting a general infection, there are 
also extremely pathogenic germs which may remain in the intestine 
without harmful consequences for a day or so. 
Physiological Conditions of Spore-formation in Aerobic Bacteria. I 
- — Herr 0. Schreiber has found that the physiological conditions which 
determine endogenous spore-formation in Bacillus anthracis, subtilis, and 
tumescens are as follows : — Prolonged and active growth occurring 
under favourable conditions never excites spore-formation. Insufficient 
nutriment and unfavourable external conditions are either detrimental to 
spore-formation or arrest it altogether. Sudden stoppage of growth pre- 
ceded by good nutrition at once provokes rapid and perfect spore-forma- 
tion. The substances which inhibit growth, and, in consequence, favour 
spore-formation, are — carbonate of soda, sulphate of magnesia, chlorate 
of soda, and distilled water. The presence of atmospheric oxygen is a 
specific and necessary condition of spore-formation of aerobic bacteria. 
Two Filament-forming Bacilli.§— Dr. L. Catiano describes two 
chromogenic bacteria which are obtained from vaginal secretion. Bacillus 
* Cf. this Journal, 1894, p. 383. 
T Zeitschr. f. Hygiene u. lnfektionskr., xxii. p. 12. See Centralbl. f. Bakteriol. 
u. Parasitenk., l te Abt., xx. (1896) p. 458. 
x Centralbl. f. Bakteriol. u. Parasitenk., l te Abt., xx. (1896) pp. 353-74, 429-37. 
§ Beitr. z. Biol. d. Pflanzen (Cohn), vii. (1896) pp. 537-41 (2 pis.). 
2 z 2 
