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SUMMARY OF CURRENT RESEARCHES RELATING TO 
nerves is of the following character: there are the usual peripheral 
nerve-bundles, the separate fibres of which either arise directly from 
ganglionic cells or from the central nervous plexus, which, on its part, 
is formed from the processes of the ordinary ganglionic cells. Two 
colossal fibres are present, one of which always arises directly from a 
colossal ganglionic cell of the opposite side; this cell is connected with 
the central nervous system as well as with its fellow of the opposite side 
by branches which break up in the central nervous plexus. Another 
and larger peripheral fibre, which is a branch of a central colossal fibre, 
has its origin in the central nervous plexus. The author’s observations 
on the tubicolous Polychaeta were not extensive. Of the Oligochaeta he 
gives a fuller account ; each pair of nerves arises thus : in the first place 
the nerve has fibres from the same and from the opposite side of one and 
the same ganglion. It also contains fibres which arise from the pre- 
ceding and the succeeding ganglia of the same half of the cord, and also 
fibres from the corresponding ganglia of the opposite half of the cord. 
In this way the very closest connection is insured between each pair of 
nerves and the whole ventral medulla. All the ganglionic cells in the 
medulla of Lumhricus are more or less multipolar, and this is true of 
even the lai gest cells. These last are pyriform in shape and appear to 
have been seen by Friedlander, who places them in connection with the 
median colossal fibre. The author will only remark that these cells are 
very large in comparison with the others, and always possess several 
processes. The largest of these processes is always directed upwards, 
while the others are very small and are lost in the nervous plexus. He 
is able to confirm and extend Friedlander’s statements as to the peculiar 
chemical characters of these cells. The double mode of origin of the 
peripheral nerve-filaments in Sijpunculus from the ganglionic cells on 
the one side, and the nerve-plexus on the other, was distinctly seen. 
The result of Herr Haller’s work is to show that the nerve-trunks of 
the Nemertinea show very archaic characters, and that the central 
nervous system of Annelids is, histologically, very different from that 
of the Vertebrata. There is ample histological evidence to support the 
view of Gegenbaur and Haeckel that the Annelids generally are not to 
be regarded as stem-forms. The Nemertinea appear, on the contrary, 
to be very old stem-forms, from which, on the one side, the Mollusca, 
and, on the other, the Annelida, Hirudinea, Arthropoda, and Vertebrata, 
can be derived. On these points the author enlarges somewhat. 
We have only space to note some of the results regarding more 
minute points ; Herr Haller finds a distinct basal membrane under the 
hypodermis which separates the latter from the perineural plexus and 
therefore from the neurilemma, while forming an organic whole with them 
both. The perineural plexus round the ventral medulla has different 
chemical characters from that in the brain. In the free-living Polychmta 
there are, within the central fibrous mass, two intercoil ed but not con- 
nected plexuses ; one of these is coarser and belongs to the neuroglia, 
while the other is much more delicate and is related to the processes of 
the ganglionic cells and to the peripheral nerve-fibres. The neuroglia 
itself consists of an outer and an inner plexus ; the former is wide- 
meshed and surrounds the whole of the nervous parts of the brain and 
ventral medulla, and contains the ganglionic cells in its interspaces. 
