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166 
This weight was also greater in summer than in win- 
ter. Notwithstanding the great variation of weight 
at birth, the difference diminished with age, all the 
animals thus tending to approach a certain standard 
size. One of the most important facts discovered 
was, that the rate of growth diminishes continuously 
from the time when the animal recovers from the 
loss of weight at birth; this diminution being rapid 
- at first, and slower afterward. Byrateis here meant, 
not the absolute increment in weight in a given pe- 
riod, but the per cent of the weight at the beginning 
of the period, which is added to said initial weight 
during the period. A discussion of the best availa- 
ble data indicates the result to be also true of man. 
Dr. Minot had also made some experiments with 
rabbits, and compared the results with those for 
guinea-pigs and forman. He found that the guinea- 
pig grows on an average, until it is full-grown, 1.78 
grams per diem, the rabbit 6.20, and man 6.60 grams. 
Men are therefore larger than rabbits, not because 
they grow faster, but because they grow longer; while 
rabbits are larger than guinea-pigs because they grow 
faster. The rate of growth, however, as above de- 
fined, is very different; being 4.6 % in the guinea-pig, 
5 % in the rabbit, and 0.02 % in man. 
Phi'osophical society of Washington. 
Jan. 5. — Prof. J. R. Eastman discussed the Roch- 
ester (Minn.) tornado of Aug. 21, 1883, describ- 
ing the ground as it appeared a few days after the 
storm, and showing that the phenomena did not 
indicate cyclonic motion. Al] disturbed objects were 
thrown in essentially the same direction, and were 
pressed down rather than lifted. In the course of 
the ensuing discussion, Mr. W. H. Dall described 
SCIENCE. 
similar phenomena in the Escanaba region, where he 
observed storm-tracks consisting of swathes of pros- 
trate trees, the trunks of which pointed uniformly ~ 
in one direction. 
Mr. Dall then read a paper on Recent advances in 
our knowledge of the limpets, summarizing the 
researches of Spengel on the sensory organs or 0os- 
phradia; Cunningham, on the renal organ and reno- 
pericardial pore in Patella and Patina; Fraissé, on 
the eye in Patina, Fissurella, and Haliotis; and the 
speaker, on the presence of an intromittent male 
organ in Cocculina. He stated that among the Ac- 
maeidae and Patellidae the type of eye differs; and 
while in Patina it is of a very rudimentary charac- 
ter, in other genera it might be well developed, —as, 
for instance, in Ancistromesus, which has as well 
developed eyes as Fissurella. He also alluded to the 
gradual progress in classification afforded by anatomi- 
cal investigation during the past few years, and 
observed that nearly all the known forms except 
Propilidium and Scutellina were amenable to classi- 
fication; our ignorance of the branchiae in the for- 
mer, and the dentition in the latter, operating to 
prevent a final classification in these two cases until 
more is known. Those authors who study the em- 
bryology and histology usually from a single species 
generally ignore the wide differences of adult anat- 
omy between the genera of limpets, and sow their 
generalizations on a basis of classification which is 
little in advance of that of Lamarck and his imme- 
diate successors. 
The president of the society, Dr. James C. Welling, 
announced the death, since the last meeting, of Gen. 
A. A. Humphreys, one of the founders of the so- 
ciety, and pronounced a brief eulogy on his character. 
q 
Q 
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INTELLIGENCE FROM AMERICAN SCIENTIFIC STATIONS. 
GOVERNMENT ORGANIZATIONS. 
Geological survey. 
Geoloyical notes. — Prof. I. C. Chamberlin and his 
assistants, during December, 1883, were engaged in 
field-work in Hlinois and in Missouri. Professor 
Chamberlin devoted his personal attention mainly 
to the borders of the newer drift, the concentric mo- 
rainic belts that lie within it, and the contiguous old 
drift without it, in north-eastern Illinois. Mr. R. R. 
Salisbury continued his previous observations of the 
residuary clays and loess and drift-borders in eastern 
and central Missouri. 
The revision of the manuscript of a report by Mr. 
J.S. Curtis on the Eureka mines has been completed 
by Mr. G. F. Becker and Mr. Curtis, and will soon 
be ready for the printer. 
Since the beginning of Prof. R. D. Irving’s study 
of the metamorphic rocks in 1882, he and his assist- 
ants have made five hundred thin rock-sections. Of 
this number, written descriptions of three hundred 
have been prepared. They include rocks from the 
original Huronian, the Huronian of the Marquette 
and Menominee regions, the Animikie group of the 
national boundary, the folded schists of the same re- 
gion, and the crystalline rocks of the Minnesota and — 
Mississippi valleys. 
Assistant John Chaplin at Denver has prepared 
thin sections of all the eruptive rocks collected in 
the Rocky-mountain district during the past season. 
Paleontology. — Prot. L. F. Ward has completed 
the work of preparing index slips for a catalogue of — 
fossil plants. He has so arranged all of the fossil — 
plants collected from the Laramie and Fort Union — 
groups, that they are in a convenient form for future 
detailed investigation. 
Chemical division. — The analyses of waters from 
Walker Lake and Walker River have been conn 
by Prof. F. W. Clarke. 
Mr. J. W. McGee, in his examination of the sulbbem 
ranean forest exposed by an excavation on Connecti- 
cut Avenue, Washington, D.C. (referred to in Science 
of Nov. 30, 1883), discovered an earthy blue mineral, 
which was abundantly distributed throughout the 
if 
