334 Brown.—Shi dies in the Physiology of Parasitism. I. 
tissue is now to a large extent a mush even without the disturbance 
incidental to the addition of a cover-glass. 
Thus in the present case, while the tissue coherence becomes reduced to 
a negligible quantity in thirty minutes, the cells themselves in the most 
sensitive region are all alive at this stage, and a certain proportion are still 
alive after seventy-five minutes. 
The following represents a summary of similar experiments in this 
connexion : 
Turnip {white) discs : coherence gone in 15'; considerable proportion of plasmo¬ 
lysable cells after 20'; this proportion much reduced after 30'. 
Cucumber discs (weak extract employed): coherence gone in 25'; large propor¬ 
tion of plasmolysable cells after 45'; this proportion much reduced after 6o'; only an 
occasional plasmolysable cell after 90'. 
Turnip {white) discs (weakened extract): coherence gone in 90'; proportion of 
plasmolysable cells undiminished after 120'; proportion distinctly decreased after 
I 35 / > hut a fair percentage of plasmolysable cells still remains after 150'. 
Turnip {Swede) discs of ^ mm. thickness (weakened extract): coherence gone in 
40'; proportion of plasmolysable cells undiminished at this stage, also at 50' and 
55'; slight reduction after 6o', but still considerable proportion of live cells after 70'; 
number of plasmolysable cells small after 90'. 
As comparable with the preceding may be cited certain experiments 
with the stamina 1 hairs of Tradescantia virginica. These are rapidly 
disintegrated by the fungal extract, so that after a time it is easy by gentle 
shaking to cause them to break up into their individual cells ; if treated at 
this stage with 5 per cent. KNO s the cells are found to be almost universally 
plasmolysable. 
On the other hand, cases were found where this time separation of 
macerating and lethal effects could not be effected. This was the case with 
sections from the fleshy leaf of Cotyledon arborea , and also to a less extent 
with sections from old white Turnip. Here it was found that at the stage 
where coherence was lost considerable disintegration of the cell-walls could 
be demonstrated and a large proportion of the cells were no longer plasmo¬ 
lysable. 
Summing up, the action of the extract on living tissue is as follows: 
The first noticeable change is the solution of the middle lamella, 
so that the tissue loses its coherence. At the stage which is termed 
‘ coherence gone this action has progressed so far that the middle lamella 
has lost its mechanical properties as a solid layer ‘cementing’ the cells of the 
tissue together. As a consequence the tissue readily falls apart along the 
line of the middle lamella. At this stage, however, the remaining layers of 
the cell-wall possess in some degree their original mechanical properties, and 
the cells themselves are quite alive. Very soon the remainder of the cell- 
wall is disintegrated, breaking down into what appear to be flakes or 
