Aucust 8, 1912] 
NATURE 
587 
of fermenting sugars (which the living organism is 
able to accomplish), but none was found. Mr. Revis 
suggests that in the fermentation of dextrose by B. 
coli, gluconic acid is first formed, and that it is 
quite possible to explain, by successive oxidation, 
reduction, and condensation, the appearance of all 
the end-products formed in the fermentation of dex- 
trose by B, coli (Cent. f. Bakt., 2nd Abt., Bd. 33, pp. 
407 and 424). 
PraAzMOWSKI contributes an elaborate study of 
Azotobacter chroococcum to the Bull. Internat. de 
VAcad. des Sciences de Cracovie (No. 3B, March, 
1912). This bacterial organism was isolated from the 
soil and from Delft canal water by Beijerinck; it 
forms a brownish pigment and fixes atmospheric 
nitrogen. A full description of its morphology and 
development is given. True resistant spores are 
occasionally formed by it, also ‘‘vegetative spores," 
analogous to the arthrospores of de Bary. 
In the five articles constituting part v. of the Annals 
of the South African Museum Dr. R. Brom discusses 
various groups of the local fossil reptiles, describing 
in the first a new Propappus, and showing that its 
bigger relative, Pariasaurus, stood higher on its limbs 
than generally believed. Both reptiles were tortoise- 
like in habits, and probably protected themselves by 
digging in the ground. In the second he describes 
a new mosasaurian of the genus Tylosaurus, and in 
the third a cynodont from the Stormberg. More im- 
portant are certain observations in the fourth on the 
dicynodont skull, where it is stated that the 
bone in which the pineal foramen is _ pierced 
is probably a neomorph, the paired bones _be- 
hind this representing the parietals. In _ this 
connection reference may be made to a _ paper 
by the same author, in the second part of the Proceed- 
ings of the Zoological Society for 1912, on the struc- 
ture of the internal ear in dicynodonts and the 
hemology of the mammalian auditory organs, in 
which he reverts to the old view that the incus Corre- 
sponds to the reptilian quadrate, the removal of the 
latter element from the mandibular joint being fore- 
shadowed in Cynognathus, in which it has partially 
slipped out. 
In The Field of July 27 ‘‘Isaac Bikerstaffe ’’ con- 
cludes a particularly interesting series of articles 
entitled ** Some Principles of Growth and Beauty ’—in 
other words, on spirals in art and nature. In this 
final instalment, in which he deals with the spirals 
of horns, the author has cleared up a misconception 
with regard to the direction of the twist in the Cyprian 
sheep and the bharal. In those species the right 
horn has been stated to form a left-handed spiral, and 
thereby to differ from that of more typical sheep, in 
which the spiral is a right one. The difference is 
really due to the upper part of the horns of the two 
species in question having undergone a ‘ perversion,” 
whereby a change in the curve has been brought 
about. Accordingly, all sheep agree in having ‘‘ homo- 
nymous”’ horns, 
In The Queensland Naturalist for May Mr. H. 
Tryon records the invasion of the Brisbane district 
NO. 2232, v@L. 89] 
and certain other parts of Australia by a large ant 
(Pheidole megacephala), the native home of which 
is believed to be Mauritius and Madeira. In its new 
haunts it occurs in myriads, alike in the open country 
and in houses, and is a deadly enemy to most insects, 
although not, unfortunately, to aphides and various 
other species injurious to vegetation. 
In the August number of The Selborne Magazine 
the editor gives a figure of the shell of Gilbert White’s 
tortoise, ‘‘Timothy.’’ The shell, which is exhibited 
in the Reptile Gallery at the Natural History Museum, 
has lost a few of its horny plates—a circumstance 
which should have been noted in the legend to the 
figure. 
From the Transactions of the Royal Scottish Arbori- 
cultural Society, vol. xxvi., part 2, July, 1912, it is 
pleasing to note that Wiesner’s brilliant researches on 
the Lichtgenuss of plants are being followed up by 
investigators in forestry work. Wiesner’s term may 
be rendered as photic ration, or the ratio between the 
intensity (i.) of the light actually falling upon a plant 
or its parts, or its habitat, and the intensity (1.) of 
full daylight at the same time. The ratio between 
the two intensities (i. : I.) is the specific photic ration. 
In a paper on the relation of light intensity to advance 
growth—that is, to the trees which have sprung up 
in openings in the forest, or under the forest canopy, 
before regeneration fellings were commenced—Mr. 
G. P, Gordon, B.Sc., describes observations made by 
him on oak and beech forests. Graphic representa- 
tions are given, in which the number of seedlings per 
o’8 square pole for each species of tree is plotted 
vertically, while the specific photic ration is plotted 
horizontally. The curve for oak indicates that as the 
light intensity increases the number of seedlings per 
unit area of the advance growth increases, reaching 
a maximum when the light intensity is one-fourth 
that of full daylight, and that large variations in light 
intensity are associated with comparatively small 
changes in number of seedlings. The curve for beech 
is very different, there being a comparatively large 
variation in seedling number for a small variation in 
light intensity, while the maximum is reached at one- 
fortieth the full daylight intensity. The author con- 
cludes by pointing out the practical importance of 
the Lichtgenuss method in forestry. 
AN excellent memoir on the North American species 
of the water-lily, genus Nymphza, has been published 
by the Smithsonian Institution (Contributions from 
the U.S. National Herbarium, vol xvi., part 3). The 
authors of this monograph, Messrs. Miller and Stand- 
ley, rightly point out that there are some groups of 
plants the taxonomy of which cannot be properly 
understood from ordinary herbarium material, which 
in the case of succulent plants is often practically 
useless. This appears to apply also to aquatics, and 
this memoir represents a remarkably successful 
attempt to revise the knowledge of an interesting 
genus in the light of the examination of fresh living 
material from all parts of a large country. Several 
new species are described, raising the number for the 
United States to nineteen, and in all cases the de- 
scriptions are accompanied by figures of the leaf out- 
