264 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
responsible for the nomenclature B. termo. The organism corresponds 
with sufficient accuracy — allowance being made for the somewhat 
vigorous treatment in staining — with the measurements, and also with 
the behaviour in cultivation, of Cohn. The staining was effected by the 
method of Loeffler — modified, I understand, by Mr. Dowdeswell — tannin 
and iron sulphate being used as a mordant. The photographs exhibited, 
and about ten others not shown, were obtained with an apochromatic 
2 mm. glass by Zeiss, projection ocular, and a dry condenser, nominally 
of N.A. 1, also by Zeiss. 
The preparation viewed with the named objective and compensating 
oculars Nos. 8 and 12, shows the flagella apparently as long and almost 
as wide as they are shown in the photographs. That is to say, that the 
flagellum so viewed varies from twdce to six times as long as the “ body 5 ' 
of the organism, and in some cases the flagella seem to be even longer 
in proportion to the bodies than six times. 
I agree with Dr. Dallinger that, as a rule, B. termo , unstained, or 
slightly stained, or stained without the use of Loeffler’s mordant, shows 
a flagellum about one and a half times the length of the body. Until 
I saw late preparations by Mr. Dowdeswell, 1 had never seen flagella 
nearly so long attached to B. termo . 
Dr. Dallinger appears to attribute the great prolongation as well as 
an “ extremely rotten ” appearance, or “imperfectly defined edge” to 
imperfections inherent in, or frequently found in, photographic repre- 
sentations of microscopic images. It is difficult to conceive the opera- 
tions or the optics concerned in photomicrography producing such a 
very remarkable prolongation of a flagellum as that with which we are 
dealing. But in respect of the width of the flagellum, much may be 
said on a certain shortcoming of photography. The phenomenon known 
as “ lateral development ” has a marked bearing on photographic 
images of very minute objects, such as the case in point. The silver is 
not reduced, I believe, precisely at right angles to the surface of the 
vehicle-film, there is a certain amount, varying no doubt with the nature 
and properties of the vehicle, of “ spreading ” of the silver image through 
the menstruum containing it, hence (among other reasons) a negative 
image is never quite so “ sharp ” as the image projected on the film. 
This action of lateral development takes place twice in the production of a 
print ; first, in the production of a negative ; second, in the operation of 
printing. Further, I believe that this lateral reduction takes place to a 
greater extent in printing processes where the image is revealed by 
development, and I believe that the gelatin processes of photography 
are more apt to favour this phenomenon than, for instance, albumen 
processes. 
The negatives and the prints exhibited were produced by development 
processes on gelatin films, and, moreover, the prints were left with 
surfaces more or less “matt”; and it is probably not stretching any 
point to say that the fact of the width of the flagellum on the print 
being at least 50 per cent, greater than if accurately represented it 
would be, is accounted for by the photographic imperfections I have 
named. The inaccuracy in the length of the flagella due to these causes 
is so slight as to be negligible. 
