Miscellaneous. 489 
very difficult, in the sections, to know whether this network is con- 
stituted by sections of cell-membranes soldered together by means 
of a cement or by very delicate fibres. Dissociations enable us 
easily to answer this question; they show that the nuclear layer 
consists of nerve-cells each possessing a large nucleus, a protoplasm 
so reduced that they seem to be destitute of it, and a fine enveloping 
membrane. We notice also that from each of these cells there start 
most frequently one, but sometimes two processes. These filaments 
are very delicate, and, when examined with an objective giving an 
enlargement of 400 or 500 diameters, comparable to the appearance 
presented by a spider’s thread seen with the naked eye. By several 
of them becoming grouped and soldered together, these filaments 
constitute the cross-lines of the meshes of the network which are 
observed in the sections. Among these cells reduced to their nucleus, 
which form nearly the whole of the nuclear layer, we observe 
a certain number distinguished by their larger dimensions; they 
possess a nucleus and a finely granular protoplasm, which is 
coloured yellow by picrocarmine ; from their peduncle starts a pro- 
cess which mingles with those of the small nerve-cells, and likewise 
penetrates into the punctate substance. 
By examining the boundaries of the nuclear layer and punctate 
substance we easily distinguish a great number of fibrille which 
emanate from the nerve-cells and become connected with the punc- 
tate substance. It is impossible to say what the fibrille of the 
hypodermic cells become at this level, or to know whether they 
penetrate into the punctate substance or lose themselves at its sur- 
face. These fibres, of which the origin and no doubt the functions 
are so different, in fact present such similar histological characters 
in Hunice Harassvi that itis impossible to distinguish them. The 
punctate substance itself consists essentially of a mass of interlaced 
fibrille forming a network which is more or less close in different 
regions. The spaces left vacant by the meshes of this fibrillar net- 
work are filled up by a finely granular protoplasm, which acquires a 
lilac-rose colour with hematoxylic eosine, and is perhaps comparable 
with the granular substance of the neuroglia of Vertebrates. 
The principal facts resulting from the preceding observations, and 
which seem to us to be of some interest in general anatomy, are as 
follows :—In the first place, the intimate mixture of the hypodermic 
epithelial cells and of their basilar processes with the cells of the 
nerve-fibres, from which results the difficulty of defining the brain 
in a clear and certain manner; and the absence of any histological 
character enabling us to distinguish the basilar fibrillee of the hypo- 
dermic cells from the nervous fibres. It seems to us to be inter- 
esting to point out these anatomical peculiarities, which remind us 
of the condition of the nervous system in the larvee of Annelides*.— 
Comptes Rendus, May 19, 1884, p. 1292. 
* Kleinenberg, “ Origine du systéme nerveux central des Annelides,” in 
Archives Italiennes de Biologie, tome i. p. 67. 
Ann. & Mag. N. Hist. Ser. 5. Vol. xiii. 32 
