264 DR. ALLEMAO ON THE ORIGIN AND DEVELOPMENT OF- 
facts, although in the preceding communication his observations relate only to the deve- 
. lopment of the primary bud of an individual plant, that is to say, of the growing embryo 
of a seed. He observes (Joc. cit. p. 105) that Mirbel in one of his latest essays on this 
subject (Acad. Se: Paris, June 1843), in opposing the views of Gaudichaud, demonstrates 
the fact that the circulating vessels ascend from the point of their origin in the stem, and 
thence extend to the leaves, but that he does not here distinguish the difference between 
tracheal and dotted vessels ; while, on the other hand, Gaudichaud comprehends in his 
descending system the same vessels, both vascular and fibrous: his own observations,. 
however, conform only with the theory of Gaudichaud inasfar as regards the propagation 
downwards of tracheal vessels, and with the latest views of Mirbel relative to the propa- 
gation upwards of dotted or fibrous vessels; and they are opposed to both, in respect 
to the evolution of each fibre upwards and downwards in opposite directions*. There : 
appears to me here a misprint, or complete misapprehension of the views of Gaudichaud, 
who clearly traces the source of each bud, not from the point of external growth, as Dr. 
Allemäo seems to infer, but; as I have above remarked, from the seat of its origin around 
the medullary sheath, at the “næud vital,” or point of departure of each independent 
ascending and descending system of vascular fibre. The origin of numerous distinct bud- ` 
formations around the medullary sheath, and the extension of ascending spiral vessels 
and of corresponding descending dotted vessels from each of these separately, are main- 
tained throughout by Gaudichaud in his * Rechérches Générales’ as an essential part of his 
theory; and these are minutely demonstrated in pl. 7. fig. 41, 42, 44, pl. 8. fig. 4, 5,6; &c., 
in dicotyledonous plants, and in pl. 9. fig. 1, 2, 3, 4, and pl. 10, in monocotyledonous plants. - 
In support of his theory he also gives numerous other illustrations, even foreibly quoting 
the same circumstances of the intumescence of a stem produced by a ligature, and the 
germination of an apparently budless stem, both which facts Dr. Allemäo considers to 
strengthen his own views in opposition to those of Gaudichaud. 
. A precisely analogous development to that delineated in the preceding memoir was 
pointed out by Mirbel in 1809, showing the origin and formation of similar vessels in the 
germinating seeds of Nelumbo (Ann. Mus. xiii. 471. pl. 34. fig. 19), where they are depicted 
as originating from the neck of the plumule, and branching thence into the nervures of the 
cotyledonary leaves, while others tend downwards into the growiug radicle: these several 
vessels were first observed by Bonnet, and described by him as ** mammary vessels," as 
far back as 1754. Mirbel described all these ascending vessels to be of spiral structure, 
and the others tending to and through the roots, to be strangulated or dotted vessels, 
which, though incapable of being unrolled, he considered to be only modifications of the 
spiral form, an opinion which he afterwards somewhat modified. Long prior to this (in 
1502), Mirbel read a memoir to the Institute, expounding these facts; and we find a very 
concise account by Desfontaines, of these able researches, in the 5th volume of the * Annales 
du Muséum’, p. 80, with two elaborate plates, showing the ascending system of spiral 
_-*® His words are, * conforma se com a theoria de Señor Gaudichaud quanto 4 propagacäo de alto 4 baixo, sómente 
, Para as tracheas ; e com as observacoes ultimas de Mirbel quanto 4 propagacäo de baixo para cima, mas unicamente 
para 08 vasos pontuados e lenhosos ; e emfim differe de todas quanto a evoluçäo de cada fibra em sentidos oppostos 
para cima e para baixo." | 
