246 
On the Structure and Development of 
9. Elastic Tissue (Fig. 8). — We have thus far omitted the 
discussion of elastic tissue for the reason that it is different from 
the other tissues already described, both microscopically and 
chemically, though often combined with them. It is also con- 
venient to class it by itself for other reasons, chief of which are 
that its corpuscular elements have not yet been definitely shown in 
adult tissue. Virchow, some years ago, stated that this tissue, as 
well as other connective substances, was composed of networks, the 
substance of the fibres containing certain markings, and he inferred 
that these might be the corpuscles of the tissue. Elastic fibres were, 
however, according to him and others, nothing but the ordinary 
fibrous tissue condensed. Each fibre was hollow and capable of con- 
veying the nutritive juices. 
Henle in his earlier writings regarded the elastic fibres as 
originating from the nuclei, of which in fact they were prolon- 
gations. Subsequently, he seems to have believed that the fibres 
originated in the basis substance (op. cit.). 
Reichert could not trace the connection between the nuclei and 
the elastic fibres, and when the latter had formed the former had 
disappeared. 
Boll, however (oj). cit.), distinctly states that the elastic fibres, 
each one constituting an "elastic cord," arise from the plate-like 
cells. 
Eanvier (op. cit.) examined tendon tissue, as mentioned before, 
but he was only able to find the elastic fibres after boiling the 
tissue for from eight to ten hours. It is proper to remark, how- 
ever, here that elastic fibres are very uncommon in tendon tissue ; 
at least they have not often been observed. 
The fibres of the elastic substance are pretty readily recognized 
by the fact that they are not coloured by carmine or hsematoxylin, 
and do not swell with acetic acid ; they branch dichotomously, 
these branches forming, with similar branches of other elastic fibres, 
networks ; this is the general form of adult elastic tissue, and it is 
probable that exceptions to this rule are, at the most, extremely 
rare ; this form prevails in the ligamentum nuchas of the ox, in the 
elastic coat of large arteries and veins, in the serous membranes 
generally, and in the subcutaneous connective tissue of the skin, as 
well as in the delicate intermuscular tissue already described. It 
will generally be found that where this tissue occurs in bundles it 
is not because there are no meshes, but rather because the meshes 
are compressed laterally, so that they are not apparent unless most 
carefully teased apart. When such fibres are broken off, their 
extremities curl up; further, the fibres are unaffected by boiling 
solutions of strong acids and alkalies, such as 35 per cent, solutions 
of caustic potash or nitric acid (standard preparations in common 
use in laboratories), unjess the action is prolonged for a consider- 
