502 
NATURE 
[March 29, 1883 
Griscom was extremely exhausted ; but on the fortieth, 
after he had been refreshed by a rather long excursion on 
the lake, the corpuscles returned to a normal condition, 
except as regards size. This improvement was not lost 
during the remainder of the fast, though the abnormal 
appearance to some extent returned. 
In the joint section of Geography and Geology are 
some interesting papers—one, the substance of an evening 
le.ture, describes the Grand Cafion of the Colorado 
River, and shows that the denudation, of which it is a 
onsequence, commenced in Middle Eocene, and has been 
Continued to the present time, the greater part however 
aving been accomplished by the end of the Miocene. 
During the whole period there has been a vertical uplift 
of from 16,000 to 19,000 feet, and a removal of a total 
thickness of rock equal to about 10,000 feet. 
Another interesting paper connected with physiography 
is by Mr. J. W. Spencer, ‘Notes on the Origin of the 
Great Lakes of North America,’ together with one by 
Mr. W. Claypole, on ‘‘ Evidence from the Drift of Ohio, 
Indiana, and Illinois, in support of the Preglacial Origin 
of the Basins of Lakes Erie and Ontario.” The authors 
discuss the physiography and geology of the districts in 
which these lakes are situated, and show the most prob- 
able theory of their origin to be that they are fluviatile 
valleys of preglacial age, which during glacial times were 
obstructed by the accumulation of drift. This, aided by 
submergence owing to change of level, has produced the 
lakes in their present form. These papers are well worth the 
study of some English geologists, to whom no work seems 
too small or too great for a glacier, and whose faith at 
one time seemed quite equal to gulping down Lake 
Superior itself, Sooner than falter in supporting a fas- 
cinating theory. 
We would venture in conclusion to suggest to the 
American Association one improvement in detail: this is to 
imitate the British, and give their volume a cloth binding 
instead of sending it forth merely stitched in a paper 
cover, so loosely as to tumble to pieces after a few days’ 
use. T. G. BONNEY 
PRINGSHEIM’S BOTANICAL YVEAR-BOOKS 
Jahrbiicher fiir wissenschaftliche Botanik, Herausgegeben 
von Dr. N. Pringsheim. Vol. XII. Part 4, and Vol. 
XIII. Part 3. (Leipzig: W. Engelmann, 1881 and 
1882.) 
“| Mie two parts now before us include six papers dealing 
with anatomical and physiological subjects, illus- 
trated by 13 plates, some of them of great beauty. In 
the concluding part of vol. xii. there are papers by 
Westermaier, Ambronn, and Zimmermann; while in the 
third part of vol. xiii. the editor, Dr. Pringsheim, contri- 
butes a long controversial paper, and there are two papers 
—a long one by Godlewski, and a short one by Tschirch. 
Westermaier’s paper is on the “‘ Intensity of Growth of 
the Apical Cell and of the Youngest Segments.’”? From 
an examination of figures of Dictyota, Hypoglossum, 
Metzgeria, Salvinia, Equisetum, and Selaginella, as given 
by Naegeli, Goebel, Pringsheim, Cramer, Rees, and 
Pfeffer, Westermaier concludes that the maximum of the 
increase in volume i: the apical region occurs in general 
either in the apical cell itself or in the youngest segments, 
and that taking the region which includes the apical cell 
itself and the four youngest segments, in none of the 
plants examined was the increase in volume of the apical 
cell found to be the minimum for the region. The results 
are represented graphically and afford very instructive 
curves. 
A paper on the “Development and Mechanical Pro- 
perties of Collenchyma, a Contribution to the Knowledge 
of the Mechanical System of Tissues,” is contributed by 
Dr. Ambronn, and is illustrated by six plates of micro- 
scopical sections. The Collenchyma with the prosenchy- 
matous fibres of the wood and bast form the mechanical 
system of Schwendener and Haberland. When the 
mechanical elements form separate plates, or bundles, or 
individual isolated cells, the cells are known as Stereides, 
and the whole tissue as S?¢eveome. When on the other 
hand the mechanical cells are united with others which 
are non-mechanical, as in wood and bast bundles, then 
Schwendener has distinguished them as Westome. The 
investigation of the structure of a number of plants shows 
that the Collenchyma may be arranged in bundles or in 
the form of a ring, and that in both the arrangement of 
Collenchyma and Mestome may follow a uniform plan, or 
the arrangement of the Collenchyma may be quite inde- 
pendent of the Mestome. Ambronn confirms the state- 
ment of Haberland that Collenchyma does not originate 
from any special morphological series of cells, but has the 
most variable origin: and further confirms the statement 
of Schwendener that the grouping and arranging of the 
cells depends entirely upon mechanical and not upon 
morphological causes. In Faeniculum vulgare the bast 
and Collenchyma of the external bundles are connected 
together and lie in the same radii, while in Clematis 
vitalba the bast and Collenchyma lie in the same radii 
but are not connected. In Phdlodendron eximium the 
Collenchyma forms a ring and is connected with the 
separate peripheral fibro-vascular bundles, both develop- 
ing from a zone of secondary meristem. In Peperomia 
latifolia a ring of Collenchyma is formed, but it is inde- 
pendent of the bast. These plants afford examples of 
the four great types of structure. The Collenchyma cells 
are always prosenchymatous, often two millimetres’ in 
length, or even longer, and they frequently contain 
secondary partitions, being chambered by numerous fine 
transverse walls. They always contain fluid very rarely 
with any chlorophyll. The walls when viewed in a longi- 
tudinal section present elongated slit-like pores., Other 
collenchymatous cells are more parenchymatous in cha- 
racter, and originate by secondary collenchymatous 
thickening of parenchymatous cells. The wall always 
colours blue with Schultz’s iodochloride of zinc, but is 
not coloured by the combined action of phoroglucin and 
hydrochloric acid, Wiesner’s exceedingly delicate test for 
lignin, which is coloured a fine and intense rose-red by 
the reagents. Collenchyma swells up but little in water, 
contrary to the usual opinion, and only contracts about 
4 per cent. when deprived of water. Collenchyma may 
originate from Cambium, from Meristem, or from Paren- 
chyma, but the origin is found to be unimportant. The 
strength of collenchymatous cells is very little inferior to 
that of bast fibres, which have been shown by Schwen- 
dener to equal that of wrought iron wire. 
The last paper is by Albrecht Zimmermann, “On the 
