Monthly retrospect of the medical sciences : February to December 1848 / edited by Alexander Fleming and W.T. Gairdner.

Date:
MDCCCXLVIII [1848]
Catalogue details

Licence: Public Domain Mark

Credit: Monthly retrospect of the medical sciences : February to December 1848 / edited by Alexander Fleming and W.T. Gairdner. Source: Wellcome Collection.

    9/286 page 3
    li(is Jalapa of Linnious and M'ildenow, or Ipoiitaia macrorhiza of Michaux, a native of Vera Cruz. But between the years 1827 and 1830, it was proved by no fewer than three independent authorities, that the root of commerce is obtained, not from the hot plains around Vera Cruz, but from the cooler hill country near Jalapa, about 6000 feet above the level of the sea, where it was exposed to frost in the winter time ; and that the plant which yields it, is an entirely new species of the Convolvulacete. In this country it was probably first culti¬ vated in the Botanic Garden of Edin¬ burgh, from a tuber sent by Dr Coxe of Philadelphia to Dr Christison, in 1838. Dr Graham could not describe it at that time, because, ow'ing to unacquaintance with the habits of the plant, it was forced in the stove, and died the same year, after forming numerous flower-buds. of which one only became partially de¬ veloped. In 1844, a plant from the Chel¬ sea Botanic Garden, cultivated in a cold frame in the Edinburgh garden during the winter and spring, survived in the sum¬ mer and autumn, and flowered luxuriantly in September. But the crown of the tuber was injiu-ed by frost in the subse¬ quent winter, and the tuber was thus killed. Ultimately, Mr M‘Nab resolved to try whether the plant could be reared from slips; and the experiment has proved successful. A tuber, of the size of a hazel nut, formed in the course of three months. The stem made little progress next sum¬ mer ; but when transferred to the cold frame in the spring of 1846, formed the plant which flowered in October.—Edin- hiirgh New Philosophical Journal, Jan¬ uary 1848. II.—ANATOMY, PHYSIOLOGY, AND PHYSIOLOGICAL CHEMISTRY. 6.—On the Nucleus of the Animal and Vegetable Cell. By Dr Martin Barrv.— Schleiden ascribed to the nucleus of the vegetable elementary cell the power of forming around it a membrane which be¬ came the cell-membrane or cell-wall ; hence he gave to the nucleus the name of cytoblast. But with the formation of the cell-wall he conceived the function of the nucleus to cease ; and thought that, being no longer required, it became inert in the cell-wall, or in some instances was ab¬ sorbed. The nucleus itself w’as, in the first instance, produced by a similar mode of development, being deposited around a smaller body, which sometimes remained as a permanent nucleolus. The same view of the formation of cells w'as advocated in relation to the animal tissues by Schwann, Muller, Henle, and \'alentin, the last of whom thus describes the process :—“ In a fluid there are precipitated granules, which are nucleoli ; around the nucleolus there is deposited a finely granular sub¬ stance, by which there is formed the nu¬ cleus (cytoblast) ; and around the nucleus there is formed the membrane of the cell. The principle of formation of the nucleus around the nucleolus, is essentially the same as that of the cell around the nu¬ cleus.” To borrow thq language of the botan¬ ist, the preceding physiologists consider the vegetable animal cell to have an “ exogenous” development ; the primitive nucleolus remaining central, and the sub¬ sequent fc-mations being deposited layer by layer around the nucleolus, which, so long as it remains at all, retains the same relative position. This view Dr Barry conceives to be incorrect, and propounds a theory of cell-development which cor¬ responds much more closely with the type of structure called in botany “endoge¬ nous.” Dr Barry describes the develop¬ ment of the cell as being analogous to that of the mammiferous ovum. Accord¬ ing to him the original granule or nucle¬ olus gradually enlarges, and in time de¬ velops within it a second body, which, appearing at first as a pellucid point, comes to occupy the position and assume the form of the original nucleolus, which has now’ expanded into a nucleus (the cytoblast of Schleiden). Thus the primitive forma¬ tion becomes peripheral, while the second¬ ary nucleolus occupies the central posi¬ tion. The same law is pursued in the further development. The nucleus or cytoblast becomes a cell, and the second¬ ary nucleolus becomes in its turn a nucleus by the development ivilhin it of a tertiary formation, which assumes the position and functions of the nucleolus. In the complete cell thus formed there are three parts—1st, the cell-membrane, or cell-wall of Schleiden, which is the original or primanj nucleolus ; 2d, the nucleus (cytoblast of Schleiden), which is the secondary nucleolus ; 3d, the true nucleolus of Schleiden, which is the terti¬ ary or last developed nucleolus of Dr Barry. According to this theory, therefore, cells arc developed endogenously : the first formed parts being always found at
    digitised image 1
    digitised image 2
    digitised image 3