590 
THE ORIGIN AND NATURE OF FAT, 
injection of a watery solution of ammonia into the lungs 
of living cats and dogs, and the subsequent examination 
of the paths pursued by the tinted fluid, the lungs being 
at once removed from the body and frozen, and the 
blood-vessels being in most cases injected with a solution 
of gelatine tinted blue. In such experiments it was found 
that, in opposition to the effect produced in dead animals, 
neither the intercellular substance, nor the cell formations, 
not even the columnar epithelium of the bronchia, with which 
the carmine solution must have been in direct contact, be- 
came tinted. The commencement of the lymphatic system 
was not exactly the same in the bronchia and the alveoli of 
the lungs. In the bronchia the epithelium generally re- 
mained uncoloured ; but between the columnar cells were 
special structures, very similar in form to these cells, and 
staining strongly with carmine. From these structures 
minute canals penetrated perpendicularly to the surface of 
the mucous membrane, and formed a close plexus in the 
submucosa, and partly also in the mucosa, from which larger 
trunks originate, which accompany the bronchia to the roots 
of the lungs. In the alveoli of the lungs, on the other hand, 
a peculiar plexus, composed of tubes and nodal dilatations, 
is found ; the latter are triangular, stellate, or irregular cavi- 
ties, which are again connected with the lumen of the alveoli 
by means of very fine tubules. The lymphatic plexus of the 
alveoli gives origin to larger vessels, which accompany the 
veins to the roots of the lungs. This system constitutes the 
so-called deep plexus of lymphatics of the lungs. The su- 
perficial plexus arises from the subpleural alveoli. The trunks 
pass into the pleura, and then into the pulmonary ligaments. — 
The Monthly Microscopical Journal . 
THE ORIGIN AND NATURE OE FAT. 
In the Transactions of the Vienna Royal Academy , Herr 
Toldt has recently published some very interesting observa- 
tions, in opposition to the statements of Virchow, who 
maintains that fat-cells are to be regarded as the cells of 
connective tissue filled with an oily fluid, and are, therefore, 
constantly associated with this tissue. Toldt gives as the 
general results of his inquiries upon the intra-spinal fatty 
tissue that this, at least, is an organ of a peculiar nature, 
which neither in regard to its structure nor function can be 
included amongst the connective tissue formations. In order 
