Novi “IDGUL OF THE TERRESTRIAL ISOPODS. 87 
seen at intervals along it. Occasionally nucleus-like structures 
may be seen in the thickenings in carmine preparations, and it 
seems probable that these are coelomic cells which have wan- 
dered into the thickening from the exterior. 
The chief interest in the thickenings, however, lies in the 
fact that they form the bases of support of a number of peculiar 
fibres, or columns, which extend inwards from them through 
the substance of the epithelial cells (Fig. 5, sf). Huet (’83) has 
described these fibres in the following words: ‘Cependant on 
voit alors qu’elle (la membrane chitineuse) envoie au travers de 
celle-ci (la couche épithéliale) dans les intervalles méme qui 
séparent les éléments épithéliaux de petits tractus, de petites 
colonnes qui l’unissent a la tunique conjonctive propre.” He 
apparently considers the columns to be chitinous in structure, 
describing them as appertaining more especially to the chitinous 
membrane. Ide (92), however, takes strong exception to this 
view, maintaining that they are protoplasmic and are merely 
‘portions fortifiées du réticulum général, des séries de trabé- 
cules placées bout a bout et fortement épaissies.”’ ? 
With such widely divergent opinions before us it becomes of 
interest to have some further light upon the character of these 
fibres, and this seems to be furnished by Haidenhain’s iron- 
lack hematoxylin. In preparations treated with this stain the 
fibres stand out very clearly indeed, as they resist the decolor- 
izing action of the iron ammonium sulphate much more perfectly 
than does the cytoplasm. When the decolorizing is carried to 
such an extent as almost to deprive the cytoplasm of the stain, 
the fibres appear as deeply blue-black strands extending from 
the basement membrane to the chitinous cuticle. They occur 
especially abundantly towards the periphery of the cells, though 
they are by no means confined to that region, but very frequently 
may be seen passing through the cytoplasm in close proximity 
to the nucleus. Huet ('83), as has been stated, considered them 
to arise from the chitinous cuticle, but it seems more correct to 
describe them as arising from the basement membrane, from 
which they spring either singly or, more frequently, in groups, 
1T have not had access to the work in which Leydig mentions these fibres. I 
know of it only through a remark contained in Ide’s paper. 
