274 
Division in Spirochaetes 
questions connected with the morphology of spirochaetes. The literature 
is so extensive, and the observations so scattered, that a resume of this 
sort may make it easier to weigh the pros and cons. The preceding 
table deals thus with the evidence for longitudinal and trausverse 
division in spirochaetes. It does not pretend to be exhaustive, but it 
includes the chief statements of the best-known authorities. 
In comparing the results given above, I was struck by the fact that 
the conclusions were so seldom based on observations of the living 
organism. It is not always clear from authors’ statements whether 
they confined their study to stained preparations, but, so far as I can 
gather, the entire process of longitudinal division has been observed in 
vivo only by Prowazek (S. marchouoci, spirochaete of Ulcus tropicum, 
S. balanitidis) 1 , Schaudinn (S. pallida), Siebert (S. pallida), and Keysselitz 
and Fantham (S. anodontae ) 2 , while Schellack (S. recurrentis, S. duttoni), 
Novy and Knapp (S. recurrentis) and Zettnow (S. duttoni) are the only 
observer’s of transverse division from its first indication till the separa¬ 
tion of the daughter parasites. This seems strange, since stained 
preparations are, in a case like this, notoriously unreliable: and so long 
as these are used as sole evidence, just so long will the supporters of 
the view that spirochaetes are bacteria insist on regarding the Y-forms 
as agglutinations, and the supporters of the view that spirochaetes are 
protozoa will see in the so-called transverse divisions simply the final 
stage of longitudinal division. 
Personal observations on the division of 
Spiroceaeta recurrentis. 
Professor Nuttall kindly suggested that I should try to make some 
observations on the division of S. recurrentis (Russian strain) in vivo 
from the blood of infected mice. At first I examined, at room tem¬ 
perature, very thin films of fresh infected blood, sealed with vaseline. 
Later on I employed a warm stage (Nuttall thermostat), with a 
1 Prowazek (1908), further states, but without particulars, that he has observed longi¬ 
tudinal division in all the smaller spirochaetes, with the exception of S. dentium, S. vincenti, 
S. recurrentis (European variety), spirochaetes from the intestines of the dog and the cat, 
spirochaetes from an abscess on the lower jaw of a chimpanzee, and S. plicatilis. Keysse¬ 
litz and Blanchard also express their opinion that the spirochaetes as a group are charac¬ 
terized by longitudinal division. 
2 Perrin and Fantham both observed longitudinal division in S. balbianii up to the final 
stage when, however, the individuals died before having separated. 
