PART I.] Methods Adopted in these Investigations. 51 



developed therein — I do not say spontaneously — become altered also. I have freqtieiitly 

 observed that a slight disturbance affects the development of these minute organisms ; 

 either the forms of life previously present cease to grow, being replaced by others, or the 

 vital process becomes changed, and the manifestations of life take another direction. 



These points will become more or less evident from a perusal of the following 

 examples, which are intended to serve as illustrations of the method adopted in 

 carrying out these investigations, rather than as evidence for or against any 

 particular hypothesis. 



In order to be the better able to judge of the significance of the development 

 which might take place in substances obtained from diseased conditions, it was 

 considered of the utmost importance that definite knowledge should be acquired of 

 what developed in nitrogenous material, when it was known that no disease existed. 

 With this object in view, solutions were made of various substances, to which choleraic 

 and other discharges were added, careful notes and drawings being made of the 

 changes that occurred from day to day. 



Illiistration I. : — 



As examples of the changes which occur in solutions of ordinary organic matter, 

 the following experiments on watery infusions and decoctions of meat are selected 

 on account of the simplicity of the mixture, and as illustrative of what has been 

 stated above, namely, that slight alterations in their surroundings exert a powerful 

 influence on the forms which living matter will assume. 



(a) One ounce of carefully filtered, distilled water was placed in a test tube, and 

 a piece of raw meat (beef) about the size of a pea dropped into it, the portion being 

 carefully removed from the centre of a fresh piece of muscle. 



In the course of twenty-four hours the upper half presented a milky appearance, 

 and there was a very thin film on the surface. It consisted of minute molecules 

 (monads or micrococcus), together with long linked filaments of a larger size than 

 vibriones, which were perfectly still (Plate XVII, Fig. Ixv). The milkiness of the fluid 

 continued to increase, but the pellicle did not get much stronger, for on the third 

 day, whilst attempting to remove a little, it broke altogether and sank in the fluid. 

 On examination it was found to contain a few long filaments with monads and short 

 vibriones, among which little oval accumulations or "heaps" were seen, as if composed 

 of broken down molecules (Fig. Ixvi). The next day the vibriones were considerably 

 longer, but no other change was visible (Fig. Ixvii). On the fifth day the " heaps " 

 had increased in number; although they appear granular with a power of three 

 hundred, they are distinctly seen to be molecules by a higher power, such as Eoss' 

 ^th of an inch object-glass, except the central portion, which seems to be of an 

 amorphous nature, and reflects the light difi"erently. In contact with the particle 

 of meat was a shreddy substance, also containing heaps, in the midst of which 



