148 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
0 . Technique.* 
(1) Collecting Objects, including Culture Processes. 
New Method of Studying the Development of Micro-organisms 
and the Mutability of their Characters and Properties.! — Dr. S. 
Delepine writes as follows : — “ Those who have followed the discussions 
which have taken place between the partisans of the constancy (Koch, 
Zopf) and those of the mutability of the pathogenic bacteria (Davaine, 
Naegeli, Pasteur, Buchner), know what stress has been placed on the 
impurity of cultivations, the pathogenic properties of which seemed to 
have altered. It is evident that one of the simplest ways to solve this 
vexed question would be, instead of studying the mixed products of the 
germination of a number of spores, to isolate one spore, and follow its 
development through all its stages, and the development of successive 
generations of organisms all derived from the same original spore and 
cultivated in various media. If it were possible to follow thus the 
history of one spore and its progeny, it would only be necessary, in order 
to obtain definite results, first to consider the complete series of morpho- 
logical changes which occur, when the descendants of the same individual 
are cultivated severally in various media, then to connect certain physical 
and chemical alterations of the various media with stages of development, 
modified and unmodified, and finally to find how the properties of the 
organism at each developmental stage, are, or are not, modified by 
external circumstances. I had already attempted to carry out this plan 
by means of a dilution method, such as that used by Brefeld and others, 
since early in 1881, when working at the organisms of suppurating 
mucous membranes, a work which I gave up owing to the failure of the 
methods I was using then, and the special difficulties connected with the 
subjects. I was, however, already then able to satisfy myself that phe- 
nomena analogous to those of karyokinesis were of constant occurrence 
in multiplying bacteria and gave rise to many appearances which have 
been observed by others, though not explained fully yet. 
About the middle of last year, whilst studying the development of 
certain pathogenic moulds and other parasites, I felt again the need of 
following closely the development of single organisms. I failed by 
plate and drop cultivations to obtain the results I wanted, partly owing 
to the effects of liquefaction of certain media, or of the mobility of others, 
partly also owing to the form assumed by drops. I was then led to 
adopt a new mode of cultivation which, although not perfect in many of 
its details, has yielded results which so far have been satisfactory, and 
some of which have been exhibited this year at a meeting of the Patho- 
logical Society (May 5th). The principle of the method is to inclose a 
thin layer of the nutrient media between two parallel plates, so as to 
force the organism to grow in definite directions. Owing to the effects 
of capillarity the most fluent nutrient media become, so to speak, fixed, 
provided evaporation be prevented, and they become as available as the 
* This subdivision contains (1) Collecting Objects, including Culture Pro- 
cesses; (2) Preparing Objects; (3) Cutting, including Imbedding and Microtomes; 
(4) Staining and Injecting: (5) Mounting, including slides, preservative fluids, &c. ; 
( 6) Miscellaneous. 
t Internat. Journ. Micr., iii. (1891) pp. 339-44. See Lancet, June 13th, 1891. 
