ELASTIC TISSUE. 125 
uninjured), and torn it asunder a little, it was examined with 
the microscope; the first appearance presented was that of a 
great quantity of isolated cells, floating about in the sur- 
rounding fluid, each of which had its peculiar nucleus. (See 
plate III, fig. 12.) This easy separation of the cells is 
never seen in the same degree in the areolar and fibrous 
tissues, as they are there connected together by the cytoblas- 
tema, and by the tough fibres issuing from the cells. These 
cells of the coat of the aorta vary very much in shape. (See 
the figure.) Some are round, but most of them oblong, some 
terminate with a blunt extremity, others are acuminated on 
two or more sides, others again are prolonged into small pro- 
cesses, which again subdivide, but never extend to any great 
length. Many of them are somewhat compressed laterally. 
They all have a granulous aspect, but that appearance, so far 
as one can judge by rolling the cells about, seems to be refer- 
rible to the cell-membrane, and the contents appear to be 
transparent. The nucleus, enclosing one or two nucleoli, 
is attached to the interior of their walls. It is sometimes 
round, at others more or less elongated. These cells have 
become disengaged from the small portion of the coat of 
the artery before described. When the preparation itself is 
examined, many more cells are observed in it, and in addition 
to them, distinct elastic tissue, consisting of a network of 
minute, elastic, rough (?) (rauher) fibres, such as are found 
nearest to the internal coat of the aorta in the adult. (See 
Eulenburg, de Tela elastica, fig. 9.) It does not, however, 
present any fibres so thick as those which are found in the 
external layers of the same part. <A blighted nucleus may 
be recognized here and there in the network. What relation, 
then, do these cells bear to this still delicate, but so far as 
regards its characteristic features, perfectly-formed elastic 
tissue? Analogy would lead us to suppose them to be 
the primitive formation; I sometimes also thought, that in 
rare instances I could observe an immediate transition ; that 
I could see, for instance, one of these cells, furnished with a 
nucleus, pass continuously on one side into a small portion of 
reticular tissue, resembling in appearance the undoubted elastic 
tissue, whilst on its other side it retained its perfect cellular 
figure. But this occurred so rarely, that I am not enabled to 
