150 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
I have devised many improvements for regulating the thickness of the 
inclosed film, and making its thickness perfectly even, but these are not 
necessary to the success of the method, and their description would 
obscure its main object. Now it will appear to many that this is nothing 
else than a drop cultivation, and to others that it is a film or plate culti- 
vation. It is all this, but I claim that it is something more ; tor by 
using an interlamellar film, as I feel inclined to call it, the free surface of 
the medium is limited to the space existing between the two glass 
lamell® used, whilst in ordinary plate, film, or drop cultivations, the 
surface in contact with the air is very extensive. By the interla- 
mellar method, a side view, so to speak, of the cultivation is obtained ; 
by the drop method, a surface view. By the interlamellar method 
organisms placed at various distances from the free surface of the 
Fig. 26. Fig. 25. Fig. 27. 
A A 
Fig. 25. — Slide with interlamellar film, ready for incubation. A A, Slide rests. 
B B, Drops of sealing-wax supporting the cover. C C, Cover-glass compressing a 
drop of nutrient material. D, Very small drop of gelatin or other material con- 
taining a few spores. 
Fig. 26. — Cover-glass, with very small central drop inoculated. 
Fig. 27. — Cover-glass, with a small central streak E E containing micro- 
organisms. 
medium can be followed in their development step by step,* a thing 
utterly impossible in drop cultivation. By the interlamellar method 
it is possible to follow certain chemical changes occurring along a 
growing filament or colony extending in a direction which can always 
be determined ; f this is impossible to the same extent in drop cul- 
tivations. 
By the interlamellar method it is possible to follow for weeks the 
development of the same individual, or group of individuals, even 
in the midst of a fluid material ; this cannot be done for any consid- 
erable length of time in drop cultivations ; I feel therefore justified 
in claiming for the method some advantages. I wish, however, to 
* In this way the branching of many bacilli can be demonstrated. This branch- 
ing, which is supposed by most authorities not to exist among the Schizomycetea 
except in a spurious form, can by this method be easily demonstrated. I had, it is 
true, been led to believe in its existence from the study of organisms grown differently, 
but by this method branches may be seen to arise from definite filaments. Dr. Slater, 
who has kindly made many observations with me for the study of this point, has 
obtained results confirming entirely my views. 
f By using media containing substances capable of forming insoluble compounds 
with the products of the metabolism of micro-organisms, the gradual formation of 
these metabolic products can be followed aud demonstrated. Thus I have lately 
been able to demonstrate the formation of oxalic acid out of various substances, such 
as gelatin, starch, gum arnbic, and possibly cellulose. I have been able to show 
that the formation of this acid begins only when growing filaments have free access 
to air — a fact of great significance in connection with I’asteur’s teachings. 
