262 DR. ALLEMAO ON THE ORIGIN AND DEVELOPMENT OF 
anastomosing in a very beautiful manner: these vascular bundles or cords also, in their 
descent, reach the base of the bulb. Now, if we take one of these bundles and examine 
it in its whole length, viz. the bundle c, d, e, it will be seen that in c and d it is formed 
only of tracheæ, and that in e, besides tracheæ, it has dotted vessels on the outer side 
which extend upwards till they penetrate the leaves, /, and downwards they are in com- 
munication with the root: at f is seen a crossing of tracheal bundles, which indicates 
that the primitive bundles, instead of divaricating from each other, cross in the centre, 
although I confess that such crossing may not be real, but apparent, and owing to error in 
observation, notwithstanding that I have seen it more than once: g shows a portion of 
two roots whose vascular system is formed of a certain number of bundles, disposed in a 
parallel direction with admirable symmetry, among which are seen dotted and scalariform 
vessels, À : no true tracheæ are observable here. 
We have in this case proved the same results which are noticed among Dicotyledons: a 
great number of microscopical observations, made upon various plants under different 
circumstances, have confirmed these views, which I consider to be unquestionable. 
FRANCISCO FREIRE ALLEMAO. 
Rio de Janeiro, December 11, 1853. 
Notes by the TRANSLATOR. 
The foregoing microscopical observations of Dr. Allemäo, which seem to have been 
carefully made, are deserving of attention, inasmuch as they offer confirmatory testimony 
of the truth of certain physiological facts which stand upon record. I am enabled by 
the knowledge of his antecedent researches, published in the Proceedings of the Vellozian 
Society, to explain his object in making the above communication: he was desirous of 
testing the validity of the theory first suggested by Du Petit Thouars, and more recently 
modified and supported by Gaudichaud, which contends, contrary to the views of Mirbel 
and other eminent physiological botanists, that all woody fibres of the stem proceed from 
the nascent leaf-buds and thence descend to the radicular extremity of plants. Dr. Alle- - 
mão states (loc. ci. Exerc. Bot. p. 104) that his observations in no way tend to support 
this theory. The facts, he observes, are best demonstrated in the stem of Cucurbita 
Pepo, where the dotted vessels are extremely large and conspicuous: here no reticulated : 
vessels are found in the ultimate leaves, or even in the last and its nearer internodes - 
(merithalli), although they are found in the lower and older leaves: he observed spiral 
vessels only in the stems or leaves, as low as the ninth or tenth axil from the extremity 
of each branchlet ; from that point, as low as the fourteenth and fifteenth axil, other 
vessels are observed in the stem only ; but below this point he found them in the stem, 
and more especially in the leaves, proving that all reticulated and dotted vessels ascend 
through the stem, before they find their way into the leaves, in their progress of growth 
upwards. On the other hand, we have evidence long ago established, which may be said 
to be the touchstone of the various theories that have been advanced on this subject ;—the 
fact of the formation of a circular tumour in the trunk of dicotyledonary plants, above 
the line of a ligature tightly tied around it. This intumescence is undoubtedly produced 
