746 
occurred, while from all other positions imme- 
diate and direct orientation with anterior end 
toward the kathode followed the closing of the 
circuit. On reversing the current, it was seen 
that the animals always gained the new orien- 
tation with anterior end to the new kathode by 
turning to the right. The fact was shown that 
sudden breaking (as well as reversal) of the 
current always caused the typical motor reflex 
that is given by the organism as a response to 
stimuli of other sorts—the animal always turn- 
ing to its right. 
3. The kataphoric effect of currents of mod- 
erate intensity in carrying Chilomonas and 
suspended particles in the water toward the 
anode was shown. 
Following the demonstrations an account 
was given of the electrotactic reaction of a 
number of infusoria, and the bearing of the re- 
sults on the recent work of other investigators 
was discussed. Reference was made to the 
reactions of some of the lower Metazoa which 
resemble in many ways the reactions of the 
infusoria. 
H. 8S. JENNINGS, 
Secretary. 
DISCUSSION AND CORRESPONDENCE. 
CORRECTION TO ANDRE’S ASTRONOMIE STEL- 
LAIRE. 
THE favorable notice of André’s ‘ Traité 
d’astronomie stellaire’ contained in the num- 
ber of ScreNcE for April 19, 1901, leads me to 
call attention to the following curious error 
contained in that work, which appears to 
have escaped the notice of all its reviewers. 
In Vol. I., 2 225, the author seeks to account 
for the well-known fact of a progressive varia- 
tion in the periodic time—interval from mini- 
mum to minimum—of certain variable stars, 
and resorting to the hypothesis of a uniform 
SCIENCE. 
[N. 8S. Vou. XIII. No. 332. 
motion in the line of sight, he proceeds by 
elementary mathematical methods to derive the 
effect of this motion in altering the periodic 
time of the light variations. It is almost self- 
evident that the effect of this motion is to pro- 
duce a small but constant difference between 
the true period, and that furnished by observa- 
tion, and this result is confirmed by the author’, 
analysis when properly executed. But at the 
equation marked (2) in the text, André commits 
the algebraic error of dividing two terms of his 
equation by a certain factor, n’—n, while 
neglecting to divide the third term and obtains 
thereby an erroneous result which he inter- 
prets, correctly enough so far as the equation 
itself is concerned, as showing that the star’s 
radial velocity produces a progressive change 
in the periodic time of its light variations. He 
applies this equation to certain well-known 
variables having secular terms in their light 
equations, and derives from purely photometric 
data, numerical values for their motion in the 
line of sight, which, although plausible enough 
in respect of magnitude, are entirely wrong in 
principle. The entire section entitled ‘Terme 
séculaire’ should be suppressed since it is com- 
pletely vitiated by the algebraic error noted 
above. 
GEORGE C. Comstock. 
AN APPEAL FOR COOPERATION IN MAGNETIC 
AND ALLIED OBSERVATIONS DURING THE 
TOTAL SOLAR ECLIPSE, MAY 17-18, 1901. 
To further test the results obtained by the 
United States Coast and Geodetic Survey dur- 
ing the total solar eclipse of May 28, 1900, 
arrangements are being made for obtaining 
simultaneous observations of the magnetic 
elements and of allied phenomena over the en- 
tire globe during the next total solar eclipse, 
May 17-18, 1901.* 
* CIRCUMSTANCES OF THE ECLIPSE. 
Greenwich Mean Time. Longitude from Gr. Latitude. 
Eclipse begins May 17d. 14h. 59m. .9 51° 347.4 E. 20° 217.958. 
Central eclipse begins 17 We) BY 8 40 11.245. 27 27.68. 
Central eclipse at noon 17 We | Bs} LS) 96 51.9 E. 2 07.18. 
Central eclipse ends 17 ig) TI), 156 53.6 E. 12 49.08. 
Eclipse ends ie BO) Oe) 145 04.545. 5 38.08. 
