272 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
plasmic processes. The latter end either in “ nids pericellulaires ” 
(Bamon y Cajal) on adjacent cells, or freely between these. The neu- 
rites of the sympathetic cells pass out without dividing, and only rarely 
give off characteristic collaterals. The entrant fibres are distinguishable 
from those which pass out ; they end in fibrous branching around the 
ganglion-cells and their protoplasmic processes. These fibres also send 
nerves to the vessels. In general form the sympathetic ganglion-cells 
are not essentially different from those of the cerebro-spinal axis. 
Plasticity of Cerebral Neurones.* — Dr. J. Demoor gives an interest- 
ing description of the moniliform state exhibited by the prolongations of 
the cerebral neurones when subjected to various kinds of excitation. The 
transformation of a nervous branch into a moniliform filament involves 
considerable modifications in the multiple contacts which the cells have 
established inter se. It results in a relative individualisation of the 
neurones, which tends to lessen the association of individual cell activities. 
It may be connected with fatigue and sleep. In any case the histological 
change is evidence of the sensitive plasmic plasticity of the neurones. 
c. General. 
Problems of Nature. | — Dr. G. Jaeger has, during the last thirty 
years, made many suggestive contributions to general biology, e.g. in 
regard to the continuity of the germ-plasm, which are not so well known 
as they should be, except in so far as biological progress has absorbed 
and outstripped them. In some instances, the idiosyncrasies of this 
biologist have obscured his indubitable merits of originality. But he 
has recently found an enthusiastic editor, translator, and exponent in 
Dr. H. G. Schlichter, and the volume before us contains representative 
selections from Jaeger’s writings. As such it is very welcome. The 
zoological part deals with the origin and development of the first 
organisms, protoplasm, the laws of development, the origin of species, 
sexual selection, pangenesis, inheritance, the influence of gravity, &c. ; 
and the whole is at once suggestive and entertaining. The ediior takes 
some extraordinary liberties with the English language, and gives him- 
self away unreservedly in a glossary (after Gould). It is also regrettable 
that a selection of this sort — obviously executed con amove — should not 
have a more adequate bibliography. There should at least have been 
clear indication of the proportions which the selections bear to the 
original papers, and where these original papers are to be found. The 
page at the end of the book is quite insufficient. 
Chances of Death.lf — Prof. Karl Pearson has published a work, the 
first volume of which must rank high among recent contributions to 
evolution-theory. The book consists of a collection of twelve essays, 
five of which are reprints ; several are of more interest to the socio- 
logist and psychologist than to the biologist in the limited sense. The 
* Arch. Biol., xiv. (1896) pp. 723-52 (12 figs.). 
t ‘ Problems of Nature. Researches and Discoveries of Gustav Jaeger, M.D., 
selected from his published writings. Edited and translated by Henry G. Schlichter, 
D.Sc.’ Williams and Norgate, 8vo, London, 1897, 261 pp. 
X ‘The Chances of Death, and other Studies in Evolution,’ 2 vols. 8vo, London 
and New York, 1897, ix., 388, and 460 pp., illustrations. 
