IV. On the continuitv of the protoplasm through tho walls of vegetabie cells. 83 
reraoved by means of a pipette, and in Hs place was added a small quantity 
of concentrated acid in which the seetion was allowed to remain for a period 
°1 from 20 to 48 hours. With the seetion still lying on the slide, the acid 
'vas removed; the seetion was well washed in distilled water and stained 
oither with Jodine or Ammonia Carmine. These preparations were made 
from the cortical lissue of the stem or of the base of the leaf of various plants, 
hui tho tissue of Prunns, Ilex, Acer and Aesculus were those which were 
principally studied in detail. 
Stated generally this observer l'ound that alter such treatment although 
in some cases the protoplasmic proeesses projeeting into the pits could not 
be traced further than to the base of the pit-membrane, yet that in many 
instances it could be demonstrated that the proeesses of adjacent cells were 
directly continuous through the pit-closing-membrane. In one instance 
(Prunus ) liowever, he noticed that in a ease where the acid had only been 
allowed to act for a short time, the proeesses appeared not to be directly 
continuous, but to be united by means of a sieve-structure which perforated 
the closing membrane. 
Before criticizing Mr. Hillhouse’s conclusions I should like to say a few 
Words aboul his methods. To an external observer, whether ehemist or 
botanist, the exposure of such a delicate structure as that of a thin seetion 
of vegetabie lissue, to the action of such a powerful reagent as strong Sul- 
phuric acid, for periods varying from 22 to 48 hours, would I ihink appear 
to be somewhat severe treatment, and its lengthy use implies no little c.on- 
fidence on the part of the author in the solidily of the connecting filaments 
of the protoplasm by means of which such a continuity might be expected 
to be maintained. My own experience certainly leads me to believe that 
after treatment with concentrated acid for a much shorter time than that 
inentioned above, the protoplasmic proeesses entering the pits would cer¬ 
tainly be attacked, and much more, any protoplasmic filaments of a still more 
delicate nature. In fact if one watches the action of strong Sulphuric acid 
conlaining Molvbdic acid in solution, in Order that the protoplasm inay be 
stained, and brought more clearly into view, on sections of the living endo- 
sperm cells of Turnus communis it is seen that the threads begin to be acted 
upon in less than 10 minutes, and certainly in a half an hour, hardly an) 
trace of them can be detected, and the same thing occurs in sections which 
have been treated with Sulphuric acid alone, and subsequently stained. 
Another objection is that although such lengthy treatment may dissolve the 
cell-walls, in so doing it causes the approximation of layers of cells which 
"ere before an appreciable distance apart (being kepl apart by their cell- 
"’alls) and thus causes the protoplasmic contents of such cells to be in a like 
Banner approximated; to lie in the same plane; and even to overlap one 
a nolher, either bodily, or by means of their protoplasmic proeesses. The 
"hole seetion is so soft and non-resistent that a very slight movement of 
6 * 
