2G0 
MRS. G. C. FRANKLAND AND DR. P. F. FRANKLAXD 
In making these inoculations, it has been our practice not only to pierce the needle 
to a distance of an inch or more into the depth, but also to streak it along the surface 
of the gelatine, as in this manner two characteristic growths are obtained, the one 
along the track of the needle beneath, and the other upon the surface of the gelatine. 
In many instances the growth of the organisms is accomplished by liquefaction of 
the gelatine, and the manner in which this liquefaction takes place is often very 
characteristic, both as to the rapidity with which the change occurs and as to the 
form of the liquefied portion. The differences observed in respect of this phenomenon 
will be duly noticed in treating of the individual varieties of organisms. 
Agar-agar tube-cultivation. —The organisms were in every case also inoculated into 
similar test-tubes containing agar-agar mixture (for preparation see note, p. 259), 
and the appearances presented by their growth in this medium have been studied, 
described, and, where particularly characteristic, drawn. 
The agar-agar cultivations frequently serve to establish differences between 
organisms which, owing to their liquefaction of gelatine, do not furnish characteristic 
growths in that medium, for the agar-agar is not liquefied by any organisms, and thus 
surface-growths can be obtained in the case of those wdiich in gelatine produce only 
liquefaction. On the other hand, there are many cases in which the cultivations on 
agar-agar are but little characteristic, whilst in gelatine the same organisms present 
important marks of distinction. 
Broth-cultivations. —The organisms were also in every case inoculated into test- 
tubes containing sterile broth-peptone (for preparation see note, p. 259), and the appear¬ 
ances presented by their growth in this medium have also been carefully observed and 
described. The appearance of the broth cultivations is generally very much less 
characteristic than those in gelatine or agar-agar, the principal differences observable 
being in respect of the formation or non-formation of a pellicle on the surface of the 
liquid. 
There is, however, a special reason for carrying out cultivations in broth, and that 
is that the form of the individual organisms is generally more uniform and natural in 
a fluid than in a solid culture-medium, for in the latter the forms are occasionally 
distorted and rendered abnormal by the pressure to which they may be exposed. 
Gelatine plate-cultivations. — Not unfrequently the most striking appearances are 
presented by micro-organisms when growing in colonies on gelatine-plates. The 
colonies are often highly characteristic even to the naked eye, and they generally 
become far more so when examined by transmitted light with a low magnifying power 
(about 100 diameters) ; these appearances we have in all cases carefully described and 
drawn. 
The plate cultivations are prepared by inoculating with a needle from a tube 
cultivation into a sterile test-tube containing melted gelatine, thoroughly mixing the 
latter by agitation, then inoculating with a needle from this into a second test-tube, 
which is again mixed by agitation. The gelatine in this second test-tube is then 
