248 EXTRACTS AND ABSTRACTS FROM FOREIGN JOURNALS. 



ceived that the functional tissue of these organs was formed by an 

 almost infinite number of orbicular and sinuous vesicles, all communi- 

 cating with each other. Helvetius (1718), with some difference of view 

 as to the nature of the tissue, admitted with Malpighi the existence of 

 cells opening into one another, within each lobule, but denied the com- 

 munication of cells in different lobules. But, before him, Willis had 

 represented the pulmonary tissue as being formed of prolongations from 

 the ultimate ramifications of the bronchial tubes, not communicating 

 with each other, and which radiate towards the periphery, where they 

 terminated in a blind extremity. This theory has since gained much 

 favour, under the name of that of Reisseissen. 



M. Bourgery considers, as a previous question of great importance, that 

 which relates to the mode of preparation of the lungs : Malpighi and Hel- 

 vetius principally studied the lung when inflated ; Willis, Reisseissen and 

 his followers chiefly used injection with mercury. These two exclusive 

 modes of preparation explain the difference in the theories which have 

 occurred to different observers. M. B. himself has employed all sorts 

 of injection, but is of opinion that the lung is best studied when dried 

 and inflated, with the vessels injected, this mode allowing the deeply- 

 seated canals to be seen, as well as those at the surface, which only, are 

 visible when opaque materials for injection have been used. 



When the lung thus prepared is examined under the microscope, it is 

 seen to be composed of minute sinuous canals, in the walls separating 

 which the blood-vessels are situated. The appearance of these canals 

 is everywhere the same, whatever may be the inclination, with respect 

 to the pleural surface, of the section by which they are exposed. All 

 are equally various in direction ; the greater number, however, are more 

 or less perpendicular to the surface ; but others are occasionally met 

 with parallel, or horizontal, and being divided longitudinally, present the 

 appearance of a groove or gutter. All these canals are exceedingly 

 tortuous, and communicate with each other at their sides and at their 

 extremities, by a vast number of openings. 



Such are, according to M. Bourgery, in general, the true aerian 

 capillary vessels of the lungs. These sinuous canals, opening into each 

 other and turning in all directions, forming by their involutions an 

 intricate mesh, through which the blood-vessels pass, convey the idea 

 of a minutely divided space with innumerable tortuous branchings, and 

 uninterruptedly continuous in all parts, having no termination but the 

 entrance into it, which is at the same time the place of exit : it is, in 

 fact, the image of a true labyrinth, in three of its dimensions, and this 

 consideration has induced M. Bourgery to name these tubes the " laby- 

 rinthine aeriferous canals," in order to distinguish them from the " rami- 

 fied canals," which constitute the termination of the bronchial tree. In 

 order to comprehend the latter, we must refer to the mode of composi- 

 tion of the lobules. Each of these bodies commonly receives a single 

 central bronchial branch, which forms the common trunk of its subse- 

 quent divisions, and extends to the peripheric extremity of the lobule. 

 Starting from this central trunk, which gradually decreases in size, the 

 secondary ramusculi which constitute the ramified bronchial canals, arise 



