May 10, 1901.] 
the right to withdraw them under agreed con- 
ditions. 
The following papers were presented at this 
meeting: 
Dr. W. A. GRANVILLE: ‘Invariants of some m- 
gous under certain projective Lie groups in the plane.’ 
Dr. EDWARD KASNER: ‘The algebraic potential 
surfaces.’ 
Professor F. MORLEY : 
braic curves.’ 
Mr. GEORGE PIERCE: 
construction for 7.’ 
Professor E. W. HyDE: ‘On a surface of the sixth 
order which is touched by all screws belonging to a 
three-conditioned system.’ 
Professor L. E. DICKSON : 
groups.’ 
Professor E. W. BRowN: 
minimal surfaces.’ 
Professor W. H. METZLER: 
gates of determinant minors.’ 
Professor E. B. VAN VLECE : ‘On the convergence 
of continued fractions in the complex elements ; sup- 
plementary note.’ 
Professor W. F. Oscoop: ‘On a fundamental 
property of a minimum in the calculus of variations.’ 
Professor E. O. Lovett: ‘The geometry of quad- 
rics.’ 
Professor E. O. LOVETT: 
etry of n-dimensional space.’ 
Dr. G. A. MILLER: ‘On the groups generated by 
two operators.’ 
Dr. EDWARD KASNER: ‘The relations between 
the angles of any number of lines in n-space.’ 
Dr. L. P. EISENHART: ‘Isothermal conjugate sys- 
tems of lines on surfaces.’ 
Dr. E. J. WILCZYNSKI: ‘Geometry of a simulta- 
neous system of two linear homogeneous differential 
equations of the second order.’ 
Dr. H. F. BLICHFELDT : ‘A new determination of 
the primitive continuous groups in two variables.’ 
“On the_real foci of alge- 
“A curious approximate 
‘The hyper-orthogonal 
“On least action and 
{On certain _aggre- 
‘The differential geom- 
The summer meeting and colloquium of the 
Society will be held at Cornell University, 
Ithaca, N. Y., beginning August 19, 1901, em 
Be fencins over a week. 
EDWARD KASNER, 
Assistant Secretary. 
ZOOLOGICAL JOURNAL CLUB OF THE 
UNIVERSITY OF MICHIGAN. 
AT the meeting of January 17th, Professor 
Jacob Reighard gave a paper on ‘ The Behavior 
of Plankton Nets.’ This was based on plankton 
SCIENCE. 
/ 
745 
work done on Lake Erie in 1899 and 1900, in 
company with Professor H. B. Ward, under the 
auspices of the United States Fish Commission. 
The amount of water strained by the nets was 
directly measured by the use of a meter. It 
was thus possible to determine accurately the 
coefficient of the nets under various conditions, 
to judge as to their constancy, and to decide as 
to the correctness of the coefficients calculated 
by other investigators. The results have a 
fundamental bearing on the worth ofall plank- 
ton work hitherto done; details will be pub- 
lished in a paper now under preparation. 
January 24th, Mr. Raymond Pearl gave an 
account of work on the ‘ Electrotaxis of Infu- 
soria.’? The paper was accompanied by demon- 
strations with the projection apparatus. The 
following demonstrations were given : 
1. The reactions of Paramecium to the cur- 
rent. The orientation and movement toward 
the kathode in a weak current were first 
shown. Then by a gradual increase in the 
intensity of the current the speed of swimming 
was made to decrease, and in a very strong 
current the characteristic changes in body form 
were seen to occur. 
2. The reactions of a species of Oxytricha, 
one of the Hypotricha. It was seen that on 
making the current a part of the animals 
immediately oriented and went toward the 
kathode, while others swam in an oblique direc- 
tion more or less transverse to the current. 
Attention was called to the fact that during the 
transverse swimming the animal often jerked 
sharply to one side, the direction of this jerk 
always being the same—that is, toward the 
right side of the organism. It was shown that 
by this process of frequently jerking toward 
the right side while swimming obliquely, orien- 
tation with the anterior end toward the kathode 
was ultimately brought about. It was pointed 
out that the reason why a part of the animals 
oriented at once, while others did so only in 
the indirect way thus described, was owing to 
the different position of the axes of the body with 
reference to the anode and kathode at the time 
of making the current. When the long axis of 
the body was transverse to the direction of the 
current and the oral side was toward the 
kathode, the transverse or oblique swimming 
