940 
axis vertical may have a directive influence in the 
negative geotaxis of these animals. 
Paramecium in its ordinary movements over- 
comes the effect of the slight difference of specific 
gravity that may exist between its ends, but as the 
negative geotropism is a delicate reaction elicited 
best in the absence of other stimuli it is possible 
that it may be a passive orientation due to a 
tendency of quietly swimming animals to fall into 
a direction affording stable equilibrium. 
The specific gravity factor may be accentuated 
by ingestion of iron which lodges at first in the 
posterior end. In a control experiment with an 
electro-magnet acting at right angles to gravity 
overweighted animals which normally aggregate at 
the bottom are brought into circulation, swimming 
upward in the strong magnetic field, past the pole 
of the magnet and dispersing at some point above, 
causing a counter circulation to the bottom in the 
weaker portion of the field. 
In such experiments with overweighted animals 
we have an example of obedience to the passive 
orienting tendency in the region where they are 
buoyed up by the magnet and of resistance to it 
in the region where they are not so supported. 
Internal stimuli induced by fatigue from swim- 
ming upward cause the change to the downward 
path. The downward movement may be broken 
up by recurring compensatory movements to make 
up for any passive deflections brought about by 
the action of gravity. In the upward movement, 
on the other hand, there is unbroken continuity 
unless interrupted by extraneous causes. It may 
be called a passive or mechanical tropism. 
(To appear in the May number of the Journal 
of Animal Behavior.) 
The Land Planarians of North America, with a 
Note on a New Species: L. B. WALTON, Kenyon 
College. 
Since calling attention to the rediscovery of 
Rhynchodemus sylvaticus described by Leidy in 
18511 the species has been found in abundance 
not only in Gambier but also at Urbana, O., and 
Meadville, Pa. The material from which the 
species was originally described was placed at the 
disposal of Girard by Leidy for study in connec- 
tion with the former’s paper on the planarians of 
North America.” Inasmuch as the specimens were 
in the possession of Girard at the time of the death 
of Leidy* and were given him for use as he deemed 
1 Ohio Nat., p. 254, 1904. 
2 Ann. Sci. Nat. Hist. Zool., p. 145, 1894. 
51. ¢., p. 153. 
SCIENCE 
[N.S. Vou. KXXXV. No. 911 
best, it is quite probable they are in the possession 
of some of the European museums, if in existence. 
Thus far it has been impossible to locate them, 
however. 
Two specimens of a much larger species approxi- 
mating 20 mm. in length and uniformly dark blue 
in color have also been taken in Gambier. For 
this the name Rhynchodemus atrocyaneus is pro- 
posed. 
The land planarians of North America and the 
adjacent islands may be tabulated as follows: 
Geoplana nigrofusca (Darwin), Mexico and South 
America (common). Geoplana stolli Graff, Guate- 
mala (a single specimen known). Placocephalus 
kewense (Mosley), cosmopolitan in hothouses, 
original habitat unknown (common). Rhyncho- 
demus sylvaticus Leidy, East. U. S. (common). 
Rhynchodemus atrocyaneus Walton, Ohio, central 
U. S. (?) (two specimens known). Amblyplana 
cockerelli Graff, Jamaica (a single representative). 
Land planarians occur under slightly decayed 
pieces of board, sticks, ete., particularly in grassy 
plots of old orchards, or lawns, usually in asso- 
ciation with snails, the young of which they super- 
ficially resemble. The anatomical structure of the 
Ohio forms is being studied. 
(1) The Sense of Taste in Birds. (2) The Breed- 
ing Behavior of the Herring Gull: R. M. StRone, 
The University of Chicago. 
(1) Chicks, doves, ducks and gulls were studied. 
The methods employed involved soaking the food 
which was given to the birds in various solutions. 
Chicks and ducks showed a dislike for food which 
had been treated with weak acids, sweets, table- 
salt and bitters. Quantitative experiments have 
been conducted for several months with gulls kept 
in captivity. These birds show a dislike for sour 
and salty solutions even when they are weak to 
the taste of the experimenter. The work with 
sweets and bitters is not yet finished for the gulls. 
(To be published elsewhere.) 
(2) Studies were made of the breeding be- 
havior of the herring gull from the standpoint of 
modifiability, and especial attention was given to 
the voice of this bird. The report was illustrated 
by lantern slides. 
(To published elsewhere.) 
Peri-cellular End-nets in the Autonomic Cranial 
Ganglia of the Sheep: F. W. CARPENTER, Uni- 
versity of Illinois. (Demonstration.) 
W. C. Curtis, 
Secretary 
