332 Meyen’s Report for 1839 on Physiological Botany. 
both streams, acting in opposition to each other, must neces- 
sarily pass into each other and, as it were, meet together; still 
closer observation shows that only one single centrifugal and 
irresistible force draws along with it the layers of cambium 
and all the utriculi or cells. Here, where the cells formed 
from the cambium have so much the upper hand, there are a 
quantity of peculiar smaller deposits of this substance, which 
are destined for very different purposes; some fill the cells, 
while others fill the intercellular passages. 
The cambium in the interior of the cells is only visible 
when it has the form of a gummy tissue; frequently it disap- 
pears directly after its appearance, and leaves no trace of its 
ephemeral existence behind. At another time these cells se- 
parate into granular spheroids, which also only exist a short 
time ; another time one of the cells alone increases, and appears 
destined to acquire double the size of that which contains it, 
but suddenly arrested in its development it sinks again, and 
mixing with the cambium forms an amorphous ferruginous 
mass, which exists some time and then vanishes. 
The cambium in the intercellular passages is not less 
abundant; it either separates into small masses or else forms 
long threads. In the first case, the organizing substance 
passes so quickly into the utricular state, that it is often im- 
possible to follow its changes. The new cells are easily di- 
stinguished from the old ones; they are smaller, and their walls 
appear as a gelatinous tender layer. Afterwards they become 
‘stronger, larger, press themselves between the others, and 
grow together with them. In the second case, when the cam- 
bium passes through the intercellular passages in the form 
of long threads, the changes can be clearly followed nearly 
from beginning to end. After a granular cambium appear— 
gelatinous cellular tissue; a cellular tissue whose sides are 
covered with papillz ; tissue with dry, thin, and finely striated 
walls; a tissue of long distinctly bounded utriculi, which are 
connected with each other; new cells press themselves in be- 
tween these, which are thereby increased two, three, four, or 
five-fold ; at last openings in the partitions establish an in- 
ternal communication between the utriculi. 
The outer layer of cambium exists only for a short time, 
and in roots which possess some consistency it is not to be 
found. Between the cells of the first and second region there 
appear here and there new ones, which, by increasing, com- 
bine with each other and inclose the central region as in a 
sheath. They are tubular, cylindrical, and their ends fit ex- 
actly on to each other. They are at first simple, but become 
compound by the addition of new tubes which are formed in 
