JULY 25, 1912] 
NATURE 
539 
for a more extensive use of synthetic culture media, 
and a summary of a report on the teaching of micro- 
biology in colleges of the United States and Canada. 
WE have received the Livingstone College Year 
Book for 1912, which contains particulars of the 
curriculum, notes from old students, &c. The college 
is doing excellent work in training missionaries in 
the elements of medicine. 
In an interesting and well-illustrated article by Mr. 
George Shiras in the May number of The National 
Geographic Magazine on the white sheep, giant 
moose, and the smaller game of the Kenai Peninsula, 
Alaska, the remarkable fact is recorded that the first- 
named animal invariably slakes its thirst by eating 
snow, and when feeding in a well-watered pasture, 
always resorts to a snow-patch for moisture. 
In a paper on crocodilian remains from the upper 
Tertiaries of Parana, published in vol. xxi. of Anales 
del Museo Nacional de Buenos Aires, Mr. C. Rovereto 
refers two out of three species to the genus Alligator, 
with the proviso that they may belong, as they almost 
certainly do, to Caiman. The third species, which 
was described by Burmeister as Rhumphostoma 
neogaeum, is referred to the existing Indian genus 
Garialis, a reference which is less remarkable than 
it might at first sight appear, when it is borne in 
mind that crocodilians of the same general type have 
left their remains in the European Cretaceous and 
Eocene. 
In the same issue (An. Mus. Nac. Buenos Aires, 
vol. xxi.) Mr. A. Cardoso adduces evidence to show 
that wild horses were in existence in La Plata in 
the sixteenth century, and that the modern Argentine 
horse is their direct descendant, the ancestral form 
being Equus rectidens of the Pampean formation, 
which exhibits certain osteological peculiarities common 
to the Argentine horse and the extinct Hippidium. 
AN important contribution to our knowledge of the 
dentition of shrewmice is made by Dr. Augusta Arn- 
back-Christie-Linde in the June number (ser. 8, 
vol. ix.) of the Annals and Magazine of Natural 
History. Yhe formula of the typical genus Sorex is 
considered to be z.}, #.4, 77.3, and in none of the genera 
is there a canine, the tooth in Myosorex which has 
been classed as such being a premolar. The presence 
in the common shrewmouse (S. araneus), and prob- 
ably in the water-shrew (Neomys fodiens), of the 
germs of more than three pairs of incisors has béen 
demonstrated, this serving to link the Soricida with 
opossums and other polyprotodont marsupials, all 
of which probably had a common ancestry. Other 
rudiments indicate the former existence of a full 
series of premolars in shrews. In Sorex, Neomys, 
and Crocidura (musk-shrews) there is evidence of 
a rudimentary milk dentition, while there are likewise 
indications of the former occurrence in the family 
of a prelacteal dentition. F 
We have received copies of several bulletins and 
leaflets issued by the Entomological Division of the 
Canadian Department of Agriculture relating to the 
economic aspect of insects in the Dominion. In one 
NO. 2230, VOL. 89| 
| feaflet attention is directed to the damage inflicted 
on forests by insects, which is regarded as equally 
serious with that due to fires. The means of -con- 
trolling insect pests generally forms the subject of 
Bulletin No. 4; cut-worms and army-worms are dis- 
cussed in No. 3; while No. 2 is devoted to bee-culture 
in Canada. 
Tue remarkable fact that considerable quantities of 
free prussic acid are accumulated in the living tissues 
of certain plants was observed by the late Dr. M. 
Treub, and there appears to be little doubt that this 
poisonous acid is actually utilised as food material 
by these plants. Some interesting details concerning 
the occurrence and function of prussic acid in the 
cherry laurel are given by Peche (Sitzungsber. kais. 
Akad., Vienna, 1912), who concludes from his ob- 
servations that the prussic acid found in the leaves 
and other organs is produced as a direct result of 
carbon-assimilation in the green leaf-cells when ex- 
posed to light, and that it is not merely a product of 
the hydrolysis of glucosides. Peche found evidence 
that while part of the prussic acid enters into the 
building up of glucosides, some of it is transported in 
a labile form, probably in loose combination with a 
tannin, and is stored up in various tissues as a reserve 
food. 
SoME notable contributions have recently been made 
to the knowledge of the lower fungi, including the 
Chytridiacez and allied forms. The relationships of 
these lowly groups are discussed in a paper by Nemec 
(Bulletin Internat. Acad. Sci., Prague, 1911), in which 
a new genus of Chytridiacee, named Sorolpidium 
betae, is described. This parasite lives in the outer 
cortical cells of beetroot, but does not appear to cause 
any hypertrophy of the infected root. The organism 
consists of a naked multinucleate mass of protoplasm, 
which eventually acquires a wall and divides into a 
number of uninucleate portions which round off and 
become sporangia, each sporangium giving rise to a 
number of zoospores; in some cases the entire plas- 
modium becomes a sporangium, while in other cases 
still the plasmodium gives rise to a thick-walled rest- 
ing cyst, which later produces zoospores. From his 
work on Sorolpidium, Nemec considers that there is 
a close affinity between the Chytridiaceze and the 
Plasmodiophoracee, though the latter are usually re- 
garded as being nearly allied to the Mycetozoa, and 
therefore to Protozoa, while the Chytridiaceze have 
generally been placed at the base of the Phycomycetes 
or alga-like fungi. In the same journal, Nemec de- 
scribes another new Chytridiaceous fungus, Olpidium 
salicorniae, with a fine series of figures illustrating the 
various stages in the life-history. 
Tue need of a handbook on the forest resources of 
India was pointed out in the report of the committee 
of the Franco-British Exhibition of 1908, with the 
result that the Indian Government decided upon 
having such a work prepared. This important worls 
was entrusted to Mr. R. S. Pearson, of the Imperial 
Forest Service, and has just been published under the 
title ‘‘ Commercial Guide to the Forest Economic Pro- 
ducts of India*’ (Calcutta, 1912, price 1s. 6d.). This 
