182 Report OF DEPARTMENT OF BACTERIOLOGY OF THE 
the cells have lost all cohesion, that is, that the tissues are 
fully “ rotten.” Thin razor sections of carrot or turnip placed 
in living cultures or in active enzym solution pass through 
these changes in from ten minutes to an hour, although longer 
immersion may be necessary to secure the complete solution 
of the thickest pieces of intercellular substance. Meanwhile 
there is a slight thinning of the walls proper from without 
inwards, i. e., from the lamellar side towards the cell cavity, 
but this is not great and complete solution has never been 
observed either in the presence of the living organisms or in 
solutions of the enzym. In order to determine this matter 
to our satisfaction the same sections have been kept under 
observation for three weeks, with repeated measurements and 
camera drawings during this period, but there was little 
change after the first few hours. Cellulose stains (iodine and 
sulphuric acid or chlor-zinc-iodine) give clear blue reactions 
with these fully softened walls, and this reaction is the same 
even after the longest immersion. The lamination of the walls 
becomes increasingly apparent for a short time, after which 
there is no further change. 
_ In no case have we found evidence of any action whatsoever 
upon lignified or cuticularized walls. Vessels lie for days or 
weeks in the presence of the enzym with the walls unchanged 
in refractive character or other appearance or in staining 
reaction to phloroglucin. 
In order to follow the course of invasion more carefully 
blocks of fresh carrot tissue cut from near the core, with pre- 
cautions to insure sterility, have been immersed in broth cul- 
ture tubes of B. carotovorus and at varying periods of time 
after the surface tissues had begun to show decomposition they 
have been carefully transferred to absolute alcohol to kill and 
fix the organisms in place, then imbedded in paraffin and sec- 
tions cut three to twelve microns in thickness. For differen- 
tiating the wall tissues and organisms various stains have been 
tried, including Ziehl’s carbol-fuchsin and aqueous solutions 
of Congo red, ruthenium red and methylene blue. 
The best results were obtained from the use of ruthenium 
red and methylene blue. It was found that about two minutes’ 
