38 REPORT ON BOTANY, MDCCCXLI : 
the palms, the Draccenece, the Pandanece, many Aloineeoe, and 
similar plants, have such a stem. The author has overlooked 
the circumstance of the increase of the pith in the growth of 
the genuine stem, which always precedes the growth of the 
bud ; and, indeed, almost forms the latter in its first state. 
Spiral vessels grow subsequently, and attach themselves to 
the older vessels of the stem, and to the internal vessels which 
are in contact with the pith. It is, however, not correct, 
when the author compares the medullary sheath of most of 
the Dicotyledons with the central system of vascular bundles 
of the Piperacece, Nyctaginece, and AmarantJiacece. The 
latter plants, in their infancy, have only a circle of vascular 
bundles, which grow outwards by means of spiroids and pro- 
senchyma, and frequently also laterally, for the eventual 
purpose of forming a ring of wood. It is not always the case, 
that the lateral growth produces a genuine ring, but gaps 
remain between the vascular bundles, as in the JJmhellatce^ 
Cruciferm, and some others ; the AmarantJiacece, however, 
are different, as also Monocotyledons generally. They have, 
even in their very first days of growth, several rings of vascular 
bundles, of which the external one developes itself into a woody 
ring. The author has taken notice of the entangling of the 
vascular bundles in the nodes in the stems of the genuine 
Monocotyledons. I have caused this to be represented, in the 
Icon. Aiiat. Bot. part i. t. 2, f. 5, 6, I flatter myself, with 
accuracy. The author also has observed the growth of the 
vascular bundles in the cauloma. The taking the Algce as 
examples of the growth of the cells, appears to me to be 
calculated to occasion errors. 
Perhaps I may be permitted to make a few remarks on 
the formation of layers in the Dicotyledons. It is a well 
known fact, that letters, carved figures, and foreign substan- 
ces, are frequently met with in the very middle of trunks. I 
found such letters in a lime tree near Berlin, on an estate 
belonging to the deceased minister, Count von Lottum ; the 
letters on one side of the split piece were hollow, as repre- 
sented, Icon. Sel. Anat. Bot. part ii. t. 2, fig. 7, on the other 
elevated, and the cavity had evidently been filled up again with 
430 
