466 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
supports his view by the following considerations : — In the tissues and 
secretions the tubercle organism appears as a shorter or longer rodlet 
propagating itself by transverse fission. But occasionally in the sputum,, 
and always in old agar cultures, filamentous forms appear which are 
n on-septate and show true branching. These thread-like forms only 
appear on the surface of the medium, whilst in the deeper parts of tissues 
and of fluids, places to which oxygen has not free access, only the short 
rodlets are found. The rodlets do not contain spores such as are met 
with in other bacilli, though in the filaments and in the rodlets there 
are forms which possess many of the physical characters of spores, but 
are distinguished from typical endospores in various ways. Indeed, the 
illustrations impart the notion that certain oval bulgings in the course 
of filaments are intended for spores. Under certain circumstances there 
may originate in close proximity to the tubercle bacilli certain forms 
which have, in their general structure and properties, much that re- 
sembles the clubs of Actinomyces , the appearances exhibited by the 
forms being probably of inorganic origin, and the result of certain 
chemical reactions between the organism and its environment. 
Protophyta. 
Schizomycetes. 
Effect of Light on Bacteria. — Prof. Dieudonne * has used in his 
experiments principally pigment bacteria ( Microc . prodigiosus and Bac. 
jluorescens putidus) . for the reason that very slight degrees of degeneration 
can be recognised by diminished pigment production, but in some cases 
B. typhosus , B. anthracis, and B. coli commune were also used. One or 
two loopfuls of a bouillon culture grown at room temperature for 36—48 
hours were mixed with agar and gelatin and poured into Petri’s capsules, 
the under side being exposed to the light. The under surface was 
covered with a cross of blackened paper. Direct sunlight in March, 
July, and August was found to exhibit an inhibitory effect after 1/2 hour, 
and in November after 1^ hour. The indications of the inhibitory 
effect were the non-development of pigment and of trimethylamin, neither 
of which returned until the second subculture in gelatin. With M. pro- 
digiosus the inhibitory effect was further noticeable from the slow and 
slight liquefaction of the gelatin. It is interesting to note that the 
sun’s power was as strong in March as in July and August. The 
germs were quite killed in 1J hour in March, July, and August, and in 
2^ hours in November. The electric arc light (900 candles) inhibited 
in 5 hours, and killed all germs in 8 hours, while the action of the 
incandescent electric light was less marked. „ 
That the heat-rays have no inhibitory or lethal influence is shown 
by the fact that the light-rays pass through a layer of alum solution 
ltjr cm. thick, the results being as in direct exposure. By absorbing 
certain rays by means of different solutions of bichromate of potash, 
chloride of copper, ammoniated sulphate of copper, sulphate of quinine, 
and by means of the electric arc spectrum produced with a Eutherford’s 
prism, it was determined that the ultra-red, red, orange, and yellow rays 
* Arb. a. d. Kaiserl. Gesundheitsamte, ix. (1894) p. 405. See Centralbl. f. Bak- 
teriol. u. Parasitenk., l te Abt., xvii. (1895) pp. 646-7. 
