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 papillae ; 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 



