May 22, 1902] 
station the maximum amount in spring falls between 6h. and 8h. 
p.m., while the greatest frequency occurs between 8h. and 1oh. 
a.m. ; in summerthe maximum amount occurs between 2h. and 
8h. p.m., and the greatest frequency between 2h, and gh. p.m. 
In winter there are two maxima of quantity, 8h. to 1oh. a.m. 
and 6h. to Sh. p.m., while the time of greatest frequency 
coincides with first period. 
**SoLoIp ” microscopic stains prepared by Messrs. Burroughs, 
Wellcome and Co. are aniline and other dyes in a tabloid form 
easily dissolved in water or alcohol or both, as the case may 
require, and therefore most useful. They are easily preserved, 
always ready and portable. The list at present published 
includes a great variety of the most generally used dyes, as 
heematoxylin, eosin, eosin and methylenblue, fuchsin, gentian 
violet, thionine blue, &c. While admitting, from direct tests 
made with some of these soloids, their usefulness, it should not 
be forgotten that, like other short cuts, also the ‘‘ Soloid” short 
cut should only supply a necessity, but should not, and cannot, 
supplant the recognised laboratory methods. The dye marked 
** Louis Jenner stain” (eosin and methylenblue) is a good eosin 
but a bad methylenblue stain, and cannot for a moment compare 
with Czinzinski’s solution (eosinand methylblue.) Pages 3 and 4 
of the leaflet issued with the soloids, containing descriptions of 
methods of staining bacilli and blood, may be safely omitted. 
IN a series of five papers published during the last few months 
in the Journal of Physiology, Dr. H. M. Vernon has described 
numerous observations on the zymogens and enzymes of the | 
pancreas. The method ‘used for estimating the tryptic power 
of extracts depends on the digestion of measured quantities of 
finely chopped fibrin in small graduated centrifugal tubes. The 
process is completed in about half an hour, and the average 
error of experiment is only 5 to 10 per cent. The necessity of 
adopting a rapid digestion method is shown by the fact, hitherto 
aot adequately recognised, that the tryptic ferment is an extra- 
ordinarily unstable body. Thus 70 to 80 per cent. of the 
ferment in a very active extract may be destroyed in an hour by 
“4 per cent. Na,CO, at 38°. If such extracts be kept for weeks 
they gradually deteriorate in activity, and the trypsin still 
remaining undestroyed is found to be a more and more stable 
body, till finally the last portions of the ferment left may be ten 
or twenty times more stable than the first. It was accordingly 
concluded that trypsin is not a single substance, but that there 
must exist series of trypsins of varying degrees of stability. 
There are likewise series of rennins, but not of diastases, though 
is was shown that the diastatic ferments of the pancreas, of 
saliva and of malt differ from each other considerably in their 
hydrolysing action on starch. As regards the zymogens, it was 
found that the rennet ferment has a zymogen very similar to 
that of the tryptic ferment, whilst the zymogen of the diastatic 
ferment is an insoluble body. The most energetic agent in the 
conversion of tryptic zymogen into enzyme was found to be 
active enzyme itself. Thus if even 1 per cent. of an active 
extract were added to a solution of zymogen at 38°, it might 
convert a third of it into enzyme in an hour. Curiously, the 
rennet ferment was likewise liberated from its zymogen by the 
tryptic ferment, and not by the rennetic. 
Messrs. BLACKIE AND SON have commenced the issue of 
a cheap edition of Kerner and Oliver’s ‘‘ Natural History of 
Plants,” which is well known to all students of plant life. 
The work will be published in sixteen monthly parts at 
eighteen pence each, and is thus brought within the means of 
everyone who is interested in the study of botany. Used 
either as a guide or a reference book, the work is appreciated 
by all who know it, and it’ deserves a sphere of influence even 
greater than that it already possesses. 
NO. 1699, VOL. 66] 
NATURE 
87 
WE are glad to learn, from the Bulletin of the St. Peters- 
burg Society of Naturalists, that the herbarium of ‘Flora 
Rossica,” which was begun by the late M. S. I. Korzinsky, 
member of the St. Petersburg Academy of Sciences, continues 
to be issued by the Academy under the supervision of M. D. I. 
Litwinow. Six more fascicules (xiii.-xviii.) appeared lately, 
together with one fascicule of ‘‘Schedze Herbarium Flore 
Rossicz.” We also learn from the same source that M. P. V. 
Syuzev has undertaken the publication of a ‘‘ Flora Uralensis 
exsiccata.” This herbarium will comprise chiefly the flora of 
the province of Perm, but also of Ufa and Orenburg. 
A work on ‘‘ The Narym Region,” by M. A. Th. Plotnikoff 
(Memozrs of the Russian Geographical Society, Statistics, vol. x. 
St. Petersburg, 1901), contains a valuable description of a very 
interesting portion of the province of Tomsk, namely, the 
portion on the water-divide between the Ob and the Irtysh, as 
also on the rivers Ket, Parabel and Vas’yugan, which repre- 
sents mostly an immense marsh—to a great extent a lake during 
the period of high water in the rivers—and the surface of which 
is covered with a floating carpet of decayed grass and knolls of 
ground upon which low bushes of birch will grow. A general 
description of this wide region (about 100,000 sq. miles) and of 
its nearly 8000 inhabitants—Russians, Ostyaks and Ostyak- 
Samoyedes—is given by the author, who has for several years 
resided at Narym. 
ABOUT seventeen years ago, Prof. Salvatore Sardo extracted 
from the siliquee of Bzgnonza Cata/pa an acid which he called 
catalpic acid, and to which he assigned the formula C,4H,,O,. 
A reinvestigation of the products of the Catalpa fruit has now been 
made by Signor A. Piuttiand Dr. E. Comanducei, whose results 
are described in the Rendiconto of the Naples Academy, viii. 3, 
Instead, however, of obtaining an acid with the formula assigned 
by Sardo, they obtained from the immature pods a substance corre- 
sponding to the formula C;H,O,, which is shown by numerous 
evidence to be identical with /-oxybenzoic acid. In addition 
they have extracted what appears to be a combination of paroxy- 
benzoic acid and protocatechuic acid, previously obtained in other 
ways by Hlasiwetz and Barth, having the formula C,H,O,, 
C,H,0,+2H,O, but the attempt to separate the two acids has 
hitherto ended in negative results, although the other acid appears 
to have been isolated by Eykman from the fruits of ///écéum 
religtosum, Many questions suggest themselves as to the state 
in which these acids occur in the Catalpa fruit, and whether they 
are free or in combination, and it is proposed to collect a 
quantity of the fruits for further observation. 
THE additions to the Zoological Society’s Gardens during the 
past week includea Lesser White-nosed Monkey (Cercopithecus 
petaurista) from West Africa, presented by Sir William Hoste ; 
a Mozambique Monkey (Cercopithecus pygerythrus) from East 
Africa, presented by Mr. J. Bolt; a Common Viper (Vipera 
berus) European, presented by Mr. C. Spencer Bubb; a 
Hartebeest (Bzébalis, sp. inc.) from Angola, purchased; two 
Japanese Deer (Cevvus séka) born in the Gardens. 
OUR ASTRONOMICAL COLUMN. 
SATURN VISIBLE THROUGH THE CassINI Diviston.—An 
interesting circular has been issued by Mr. C. T. Whitmell, of 
Leeds, calling attention to the possibility of this phenomenon 
being observed. On July 17, 1902, at 13h. G.M.T., Saturn will 
be in opposition to the sun, and about 7h. G.M.T, on that day 
the earth and sun will be equally elevated above the ring plane, 
their Saturnicentric declination being about 22° 26’ 17” N. 
Adopting Prof. Barnard’s estimate of 2270 miles for the breadth 
of the Cassini division, and fifty miles for the thickness of the 
rings, Mr, Whitmell calculates that the effective opening of 
the division will be $20 miles, corresponding to 0” 20 in angular 
