APRIL 11, 1884. | 
Gill at the Cape observatory, and it is hoped that Dr. 
Elkin will employ it in continuing these remarkable 
measures. We believe that no method of determining 
stellar parallax, so accurate and expeditious as this, 
has ever before been at the command of astronomers. 
Simon NEWCOMB. 
CARNIVOROUS HABITS OF THE 
MUSKRAT. 
AT a recent meeting of the Biological society of 
Washington, a paper was read by Mr. Henry W. 
Elliott, setting forth an entirely new fact in regard 
to the diet of the common muskrat (Fiber zibethicus), 
proving that carp-ponds in the west are being com- 
pletely devastated by this animal. Ponds which 
should produce many carp are almost entirely barren; 
and for a long time the owners have been unable to 
account for it, no hawks being seen, there being no 
possibility of escape from the ponds, and in some it 
being impossible for other people to take them with 
a seine on account of obstructions placed in the way 
to prevent this. It was finally suggested, and after- 
wards proved conclusively, that muskrats were the 
miscreants. Carp have the stupid habit of sticking 
their noses into the mud during the winter, and hi- 
bernating; thus rendering it possible for so clumsy an 
animal as a muskrat to obtain them easily, —a thing 
which it would probably do in winter, when roots, 
etc., its natural food, are hard to obtain. If it be a 
fact that the muskrat has acquired the habit of eat- 
ing carp, immense damages are likely to result, unless 
speedy and extreme measures be taken; for, under 
these circumstances, such a sluggish and poorly pro- 
tected fish as the carp can hardly be expected to resist 
or avoid its enemy, but will become its easy prey: 
and thus one of the most important works of the 
fish-commission, from which such great economic 
benefits were expected, will result in nothing. Asa 
means of getting rid of these pests, so hard to shoot, 
and not easily trapped, poisoning by means of strych- 
nine placed in apples was suggested as the best, 
it having been applied with success in many cases. 
In his communication, Mr. Elliott asserted that in 
no monograph of the animal could he find any men- 
tion of the diet of the muskrat, other than that it 
was an exclusive vegetarian, and, so far as he could 
ascertain, this was the first time that the carnivorous 
‘appetite had ever been brought before scientific men; 
in which statement he was sustained by an authority 
upon mammals, present at the meeting. This was 
surprising to many; for it seems to be well known, 
aS was proved by the discussion which followed the 
paper, that the muskrat will, and does frequently, 
under favorable conditions, eat animal food. One 
gentleman mentioned that he had seen muskrats take 
bait, and even live fish, from his hook, while fishing 
in fresh water. The piles of Unio shells frequently 
seen upon the tops of muskrat mounds, also prove 
conclusively that it will at times eat animal food. 
It is noticed that the shells are always perfect, not 
even having chipped edges; and it would seem strange 
that this should be so, unless we supposed that they 
SCIENCE. 
457 
were left to die before being eaten, the meat then 
being easily picked out. 
The muskrat is not the only rodent which departs 
occasionally from a vegetable diet; for such animals 
as the squirrel and capybara are, and have been for a 
long time, known to eat flesh when the circumstances 
are favorable. Mice and rats, of course, are well 
known to be omnivorous, eating animal food as quick- 
ly as vegetable, this being the partial result of contact 
with man. In the other orders of herbivorous mam- 
mals, examples of deviations from the normal class of 
food are frequent, especially under domestication: for 
example, the feeding of fish to cattle; while, under 
similar conditions, the carnivorous dog and cat can 
be made to eat vegetables or vegetable products. By 
thus adding one more animal to the number of re- 
corded species which will adopt an opposite diet from 
the natural, Mr. Elliott is deserving of credit; for, not- 
withstanding the fact that it is known to some, still 
it has never been placed before the scientific world in 
any recognized monograph or treatise upon Rodentia. 
RALPH S. TARR. 
CONDITIONS OF GROWTH OF THE 
WHEAT-RUST. 
THE last part of the journal of the Royal agricul- 
tural society of England has sixty pages devoted to a 
‘Report on wheat-mildew.’ Mr. W. C. Little pre- 
pared an extended list of questions concerning the 
wheat-mildew, or wheat-rust (Puccinia graminis), 
to which a large number of answers were received 
from British farmers who had suffered from the rust. 
From these reports it is gathered, that the rust is 
more prevalent in those localities where the atmos- 
phere is most moist. Spring frosts, heavy rainfalls, 
and violent changes of temperature, encourage rust. 
Hot weather, with frequent thunder-storms, is most 
favorable for the rapid development of the fungus 
parasite. Some of the observations point toward 
the belief that about eleven days are required for the 
full development of the Puccinia after it has entered 
the wheat-plant. 
Perhaps the most valuable results of the compiled 
answers are those upon the relation of soils to the 
rust. The pest is more prevalent on peat and clay 
soils than on gravel or light lands. Drainage is a 
partial preventive of rust. High farming encourages 
the development of rust, especially if the wheat is 
rank, and it becomes lodged or fallen. There is an 
agreement of opinion that rust prevails in wheat 
sown after clover. Newly broken up lowland pas- 
tures are seldom sown to wheat because so sure to 
become rusted. 
Dr. J. B. Lawes holds the view that plants are 
liable to the attacks of parasites, either insects or 
fungi, in proportion as the soil is deficient in avail- 
able mineral food. Common tilled land contains 
about ninety-seven per cent of mineral matter, and 
three per cent of vegetable substance. The low- 
lands have this proportion nearly reversed. Dr. 
Lawes says, ‘‘ Plants are very much like ourselves: 
their power to escape disease, and to struggle against 
