DECEMBER 29, 1899. ] 
finally reached on June 22, 1897, Van- 
nutelli and Citerni, the two surviving 
members of the Second Bottego Expedition 
were most cordially received by the Italian 
Envoys—Major Nerazzini and Captain 
Ciccodicola, and arrangements were quickly 
made for their return to Europe. 
Among the perils and dangers of such a 
journey as this especially when the great 
difficulties of transport are taken into con- 
sideration, the collection of scientific speci- - 
mens is by no means an easy task. Yet, 
as will be seen by reference to the Appen- 
dix to the present volume, the members of 
the Second Bottego Expedition by no means 
neglected this part of their duties. After 
the geological, meteorological, and astro- 
nomical observations are given we find a 
summary of the zoological results prepared 
by Dr. Gestro of the Museo Civico of Genoa. 
These are based on specimens obtained 
during the first part of the journey between 
Brava and Lake Rudolf which, however, 
formed but a very small proportion of the 
whole collections. The Mammals have been 
described by Mr. Oldfield Thomas of the 
British Museum in two papers published in 
the Annals of the Museo Civico of Genoa, 
the first relating to 27 species and the sec- 
ond to 20, one of which (Crocidura bottegi) 
was new to science. The few birds saved 
from the wreck have been named by Count 
Salvadori, the Reptiles and Batrachians by 
Mr. Boulenger and the Fishes by Sigo Vin- 
ciguerra. Their reports have likewise ap- 
peared in the same well-known periodical. 
The more numerous specimens of Inverte- 
brates have been worked out by various 
specialists of whose contributions the titles 
are given here, together with an abbreviated 
account of the principal novelties accom- 
panied by many excellent illustrations. The 
value of this well prepared volume is fur- 
ther enhanced by the excellent series of 
maps attached to it, whereby every de- 
tail of the routes pursued may be followed 
SCIENCE. 
955 
with the greatest ease. The name of Gia- 
cano Doria attached to the preface isa 
guarantee that neither trouble nor expense 
has been grudged in the production of the 
present volume as is indeed at once evi- 
dent to all that examine it. 
P. L. ScuaTer. 
LONDON ZOOLOGICAL SOCIETY. 
ON THE CHEMICAL NATURE OF ENZYMES. 
THE enzymes form one of the most inter- 
esting groups of organic compounds from 
the physiological as well as the purely 
chemical point of view. Physiologically 
they may be classified as follows: 
1. Enzymes which are intimately con- 
nected with nutrition, as diastase, pepsin, 
trypsin, lipase, etc. 
2. Enzymes which cause oxidations—the 
oxidases. 
3. Enzymes which bring on coagulations, 
the clotting enzymes: rennet, thrombase, 
pectase. 
The first group has been known longest 
and best and has served certain authors for 
inferences and distinctions which at pre- 
sent are no longer tenable. Hrroneous 
views as to the réle of enzymes are however 
now and then entertained even at the pre- 
sent day, actions being ascribed to them 
which belong exclusively to the living pro- 
toplasm itself. Thus, in an article on 
‘Assimilation and Heredity’ the hypoth- 
esis was formulated that ‘‘ enzymes are 
the true bearers of heredity.”” Thus far it 
has been the well founded inference that 
the molecular arrangement, the invisible 
organization or tectonic of the chromosomes 
forms the foundation of the genetic differ- 
entiation and heredity. These chromosomes 
consist principally of a nucleoproteid (chro- 
matin) ofa very labile nature, that is easily 
converted into a stable proteid by injurious 
influences which cause their death. The 
chromatin of the chromosomes of different 
animals may not be identical, but only iso- 
