TRANSLOCATION OF NUTRITIVE MATERIALS 225 
be forgotten, however, that al] cell-membranes are per- 
forated by very delicate strands of protoplasm which extend 
from one protoplast to another. There is here a path of 
transport by which the protoplasm can pass substances from 
cell to cell as already suggested. 
We may find proofs that the pathway lies along the bast 
by experiment carried out on plants in which translocation 
is actively proceeding. If we cut a branch from a suitable 
vigorously growing tree and remove from near its free end 
a ring of tissue extending inwards through the bark and 
cortex to the cambium, and then place all the lower part in 
water or moist earth, very marked effects follow. After 
some time, perhaps a few weeks, adventitious roots will be 
put out from near its end. Those which arise beluw the 
missing ring will be few and of small size ; those from above 
this region will be numerous and strong, and will continue 
to elongate. Any buds that may be on the part below the 
ring will not develop, while those above it will grow normally 
or even more freely than on an uninjured branch. The 
tissue immediately above the ring will become somewhat 
hypertrophied and show a decided swelling. 
The continuance of the growth shows that the water 
supply has not been cut off, but the different behaviour of 
the. parts above and below the excised tissue tells us that 
the supply of nutritive material to the latter region has 
been interfered with, and the buds and adventitious roots 
it bears gradually perish of imanition. The passage of 
any food or nutritive material across the ring has become 
impossible. 
If a similar incision is made into another branch, but is 
not carried so far inwards—if, that is, the ring of tissue 
removed consists only of the structures external to the 
’ bast—these appearances do not accompany or follow the 
wound. Evidently in this case the translocation path hag 
not been interfered with. We may safely conclude there- 
fore that the transport of elaborated products, chiefly food, 
is the principal function of the bast. 
’ 15 
