Physiological Studies in Plant Anatomy 221 
digestion upon the membranes of the growing point was investi¬ 
gated. Root tips of Vida Faba L. were digested in acid peptic and 
alkaline tryptic solution, control root tips being kept in alkaline 
and acid solution of equivalent strength. All solutions were kept 
antiseptic with toluol. After several weeks’ digestion the tips were 
fixed in absolute alcohol, embedded in paraffin, microtomed and 
the sections stained with Delafield’s haematoxylin and safranin in 
70 per cent, alcohol. It could then be seen that while the proto¬ 
plasts themselves were about equally digested in both cases, the 
walls of the meristem after peptic digestion had almost disappeared. 
In an attempt to isolate the resistant substance present in the 
root tip, the radicles of Vida Faba L. taken from the dry seed were 
used, as preliminary tests had shown that sections of these radicles 
only showed traces of cellulose in the region where they joined the 
hypocotyl. The dry radicles were ground into a fine powder and then 
boiled with alcoholic potash to saponify and remove fats. The residue 
after saponification was soaked in concentrated sulphuric acid for 
twenty-four hours, then boiled in 10 per cent, acid under a reflux 
condenser for three hours to remove the cellulose. The residue after 
filtering, washing and drying was then boiled in 20 per cent, potash, 
and after being again filtered and washed on a plug of Kahlbaum 
asbestos in a Gooch crucible, was found to give a strong reaction 
for cellulose and was now completely soluble in strong sulphuric 
acid. The only explanation of the result would appear to be that 
cellulose had been produced as the result of the hydrolysis in potash. 
Sections of the dry radicles were therefore tested for cellulose after 
boiling with caustic potash for a moment on the microscope slide when 
the reaction was much more marked and more widely distributed. 
There is very little experimental evidence in the literature avail¬ 
able to us of cellulose arising from pre-existing substances, but 
Czapek(i6) ( loc . dt. p. 644) has pointed out that in the mosses the 
reaction for cellulose is usually first obtained after boiling with 
dilute alkali, while it is a general instruction in micro-chemical 
literature that the cellulose reaction is usually better after such 
preliminary treatment of the section. 
The evidence now available to us in the case of the root tip 
suggests that in the meristematic region the walls do not give the 
cellulose reaction but contain possibly more or less protein, together 
with some substance which increases in amount with time and 
which gives the cellulose reaction on boiling in potash. In the stem 
we have not sufficient data as yet about the existing conditions but 
