106 



Dr. Klein. On Infectious Diseases* [Feb. 14, 



and bacillus anthracis, our bacillus grows under favourable conditions 

 into long leptothrix-like filaments, which occasionally form more or 

 less complex convolutions. 



In these filaments highly refractive spores make their appearance. 

 These become free after the disintegration of the original filamentous 

 matrix. The fully developed spores of our bacillus differ from those 

 of hay-bacillus and anthrax-bacillus by being more distinctly cylin- 

 drical and much smaller.* According to Professor Cohn (Beitrage 

 zur Biologie der Pflanzen II, 2, 1876, p. 264) the long diameter of the 

 spores of bacillus of hay and also of anthrax — for both are identical 

 in morphological respects (I.e., p. 275) — amounts to 0*0015 — 0"0022mm. 

 or 15 J(xi(T of an inch, whereas the spores of our bacillus are little less than 

 0'0005mm. or 5 q 00 of an inch in their long diameter.f At first I 

 misinterpreted the spores, regarding them as a kind of micrococci, 

 and only after repeated observations have I succeeded in tracing them 

 through their different stages of development. 



After many failures — owing to the introdnction and development of 

 bacterium termo — I succeeded at last in obtaining, already in the 

 second generation of original virus, a pure crop of bacillus and its 

 spores. With these I started several separate cultivations, in which the 

 germination of the spores into delicate bacillus, the swarming stage, 

 the rapid multiplication by division, their growth into long apparently 

 smooth filaments, and, under sufficient access of air, the formation 

 of the bright cylindrical spores in them could be distinctly traced. t 



* In the figures accompanying Dr. Koch's paper on bacillus anthracis (Beitr. z. 

 Biologie d. Pflanzen ii, 2, 1876) the spores are represented in many places as more 

 or less spherical in shape. 



f In convolutions of filaments the outlines of these latter become gradually lost 

 after the spores are formed. The spores appear now to be embedded in a trans- 

 parent gelatinous matrix. At the edges of such masses or where they are in a 

 sufficiently thin layer, the linear arrangement of the spores can be still recognised. 

 But there is undoubtedly a transparent jelly present in these masses forming the 

 ground substance for the spores and fibres. Professor Cohn mentions (1. c, p. 263) 

 a similar jelly in convolutions of hay -bacillus. I entirely differ from Dr. Koch with 

 regard to the mode of germination of the spores of bacillus. Koch states (1. c., 

 p. 289, and also in his latest paper on Bacterisee in Biol. d. Pfl. 2 Bd. 3 Heft.) that it 

 is not the highly refractive spore which directly produces the bacillus, but that the 

 hyaline gelatinous envelope surrounding each spore elongates so as to form the 

 bacillus, while the bright spore-matter itself gradually diminishes in size and finally 

 disappears. Prom a priori reasons it is impossible to assume that this can be so, viz., 

 that the gelatinous envelope should grow into the bacillus ; for Cohn proved beyond 

 doubt that in the case of hay-bacillus the spores germinate even after having been 

 exposed to boiling heat. Surely this gelatinous envelope, if living protoplasm, must 

 become, under these conditions, deprived of its germinating power. Direct ob- 

 servation proves that in my case the spores possess another membrane within that 

 gelatinous envelope, and during germination this inner membrane is broken at one 

 pole and the contents of the spore protrude and grow out as the bacillus. This 



