82 
POPULAR SCIENCE REVIEW. 
Influence of the Hop on Fermentation. — If we are to believe the statements 
of Signor Tigri, the flowers of the hop arrest immediately the development 
of yeast. 
The Mathematics of Plant-growth. — At one of the late meetings of the 
Botanical Society of Edinburgh (Nov. 11), Mr. W. Mitchell presented a 
curious paper, entitled u On Equations to the curved Outline of the Leaves of 
Plants.” He attempts to find formulae to express the curve of the outline, 
and this is how he does it : — Selecting a characteristic and well-developed 
leaf of any plant, he carefully traces its outline when placed on cardboard or 
stout paper ; but when both sides appear to be equally developed, one -half 
the outline is sufficient. On this copy all the measurements are made. 
The point corresponding to the base of the mid-rib of the leaf is fixed on 
for the pole, or origin of measurement, and from it lines are drawn to the 
outline, making equal angles with each other. These lines are then mea- 
sured by a scale divided on the edge into tenths of an inch ; and as the first 
line, or radius vector, is the longest, we have a descending series of terms 
from which to construct a formula for the curve in question. 
The Microscopic Character of Pollen Gt'ains. — Herr Luerssen describes with 
considerable minuteness the pollen grains in the orders Onagracece, Corylacece , 
and Cucurbitacece. His memoir is to be found in the Jdhrbuch fur wissen. 
Hotanik for 1869, and is copiously illustrated. 
Eophyton explanatum. — An account of specimens of this plant found in the 
Lower Arenig rocks of St. David’s is given (with a handsome plate) in the 
Geological Magazine for December. The following is the description of the 
species named above : — A raised, moderately convex stem, about four 
lines in breadth ; widening, however, and becoming somewhat compressed 
at the joints. The surface is ribbed, and furrowed along its whole length. 
At the lower joint the ribs bend outwards, evidently to form a branch. The 
joint is obliquely placed, widened out, and its course distinctly marked by 
a deep sulcus. The cortical substance is very thin, and can be removed to 
show the internal structure. The internal structure is made up of com- 
pressed columns, running the whole length from joint to joint, evidently of 
a tubular nature, and bound together by very thin tissue. 
State Recognition of Dr. Hooker's Services. — Dr. Hooker has been m ade C.B. 
since our last Number was published. The following is the notice from the 
Gazette of November 9: — “The Queen has been graciously pleased to give 
orders for the appointment of Joseph Dalton Hooker, Esq., M.D., director of 
the Royal Botanical Gardens at Kew, to be an Ordinary Member of the 
Civil Division of the Third Class, or Companions of the Most Honourable 
Order of the Bath.” 
The Scarlatina Fungus. — Hallier asserts that scarlet fever is the product 
of a fungus which he names Tillvtia scarlatinosa. We hope it will be 
better established than his well-known cholera-fungus. He says he has 
never seen such an immense number of micrococci in the blood of any other 
infectious dinease. These are at first as small as the finest pin-point, or the 
most minute granular matter. They are present in far greater numbers than 
the blood globules themselves ; both swimming free in the serum and accu- 
mulated in granular masses and groups. They both accumulate on and 
penetrate into the blood globules. The white corpuscles as well as the red 
