ON THE LAMINAR TISSUE OF AMPHIOXUS. 
425 
mine. They represent the bodies of the cells united one 
with another, or rather, all fused together.^ 
The only tissue which approaches in histological struc- 
ture that which we are about to describe, is the tissue of 
the cornea in the eyes of bony fish. We have elsewhere 
described this tissue thus : — All the corneal cells appear 
fused together, so that it is impossible to distinguish their 
outline, the protoplasmic bodies of the cells forming a 
sort of membrane, with nuclei scattered here and there. 
The meshes of this network are small and separated by 
extremely broad rods, which forms a true lamellar system 
mixed up with the fundamental lamellar system of the 
organ, &c.”^ 
In the lophioderm of Amphioxus the meshes of the 
network are broader than the rods, and these latter are 
disposed in the same plane ; but the two tissues, nevertheless, 
present an analogy which enables one to place them side by 
side among the large number of varieties which the laminar 
tissue of vertebrates presents for our study. 
Fig. 6 shows that in posterior region of the notochord the 
nuclei are very abundant ; they are very small, and answer 
very well to the description and figure given by Stieda. 
On the other hand, they are scattered throughout the sub- 
stance of this organ, which does not agree with the opinion 
of Kossman (see ‘ Verhandlungen der Phys. Med. Ges.,’ 
Wurzburg, 1874). 
In the deep layer under the dermis in the neighbourhood 
of the mouth, the network of cells of the laminar tissue has 
not the same appearance. It presents large irregular meshes, 
with a slightly sinuous contour. The nuclei are no longer 
accumulated at the junctions of the network. The rods are 
almost cylindrical, and are swollen here and there.® These 
swellings present a larger or smaller hollow in the centre, 
bounded on all sides by the protoplasm and the nuclei, 
which are arranged in a single row. In optical section these 
hollows appear to be simply fissures between the layers of 
cellular substance. 
Sometimes these enlarge and spread to a greater or less 
extent, but they always remain very irregular. This is the 
^ It sometimes happens in certain preparations that at the inter- 
sections of tlic network there is a sort of cleavage, so that the nuclei 
appear to be each surrounded by a protoplasmic body with a polygonal 
outline. 
- G. Pouchet et Tourneux, loc. cit., p. Oil, et fig. 1G8. 
•’ These swellings, scattered on the thinnest rods of the network, have 
no doubt given rise to the error of Owsjannikow, who thought he had seen 
the cellular bodies anastomising by their prolongations. 
