356 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and establish a communication between these two parts. In the course 
of development the ganglionic layer migrates from the protocerebral lobe, 
where it arose, and passes behind the eye. In connection with this 
movement the fibres of the external chiasma elongate a good deal, while 
the postretinal fibres become shortened. After describing in detail the 
history of the succeeding lobes the author passes to the ventral chain. 
The primitive ridges form a swelling in each segment. These swellings 
become the seat of histogenetic phenomena identical with those which 
happen in the cerebral lobes. In the embryo there are fifteen distinct 
ganglia — three post-oral cephalic, three thoracic, and nine abdominal. 
The nerves are given off from the nerve-centres in the form of buds, 
which are rounded at their extremities ; these grow peripherally. The 
azygos visceral nervous system is composed of three median ganglia 
connected with one another by an unpaired (recurrent) nerve. These 
ganglia are all developed at the expense of the dorsal wall of the 
stomodfeum, which becomes invaginated in the middle line. The name 
of ectodermic intraganglionic ridge is given to a temporary structure 
which enters into the most intimate relations with the nervous system, 
though taking no part in its constitution. An invagination of the 
ectoderm near the optic plate insinuates itself between the internal and 
external medullary masses ; it becomes constricted off from the ectoderm, 
and, later, undergoes degeneration. 
Habits and Metamorphoses of Emenadia flabellata.* — Dr. A. 
Chobaut gives an account of the life-history of this parasite, and comes 
to the general conclusion that the Rhipiphoridm have two larval forms, 
which differ much from one another ; the first is truly tri-unguiculate, 
the second is like that of other Coleoptera. Emenadia is parasitic on 
solitary wasps such as Odynerus, or Eumenes. Their parasitic habit, 
which is absolutely analogous to that of Rhipiphorus paradoxus, consists 
in entirely devouring the larva of their host, as soon as it has reached 
its complete development, and at the very moment when it is passing 
into the nymph-stage ; this act it efiects as an external parasite, though 
it has previously passed all its time as an internal parasite. 
Structure of Larval Nervous System of Stratiomys strigosa.t— 
MM. Henneguy and A. Binet call attention to a curious arrangement in 
this Dipterous insect. Each ganglion of the nervous system, which is 
highly concentrated, is united to its neighbour by a pair of very short 
connectives ; each connective is formed of a bundle of fibres, which is 
nearly cylindrical in form for part of its length ; this form is not, 
however, retained in the fibrillar substance of each ganglion ; the fibres 
separate and extend through the ganglion at different planes. At the 
point where the connectives penetrate there is a cell with a very distinct 
and very large nucleus. There are in each ganglion four of these “ cells 
of the connectives.” 
From each cell a certain number of radiating fibres are given off, 
and some have several secondary branches ; these fibres and fibrils are 
lost in the connective-tissue element of the connectives. The authors 
are unable to suggest what is the function of these special cells ; they 
* Ann. Sci. Nat., xii. (1892) pp. 97-112 (6 figs ). 
f Comptes Rendus, cxiv. (1892) pp. 430-2. 
