502 
gastric juice is sufficient to produce such 
inversion as takes place in the stomach. 
The section held no session on Saturday, 
the majority of the members making the ex- 
cursion to Niagara. 
Monday forenoon was devoted to the sub- 
ject of neurology. Professor Carl Huber 
(Michigan) gave an account of his study 
of the comparative histology of the cells of 
the sympathetic nervous system. (See 
SCIENCE, Wolk Vi, p. 13825) ) Dri win Je 
Mackenzie (Toronto) spoke on the micro- 
chemistry of nerve-cells. Mr. W. B. War- 
rington gave the details of an investigation 
of the changes in nerve-cells in various 
pathological conditions, the latter being 
caused by various organic poisons, anemia, 
the division of peripheral nerves, and the 
division of the posterior roots. Professer 
A. Waller (London), who is a member of 
the committee previously appointed by the 
Association to investigate the changes which 
are associated with the functional activity 
of nerve-cells and their peripheral exten- 
sions, and who has been working upon 
the electro-physiology of isolated nerve, 
made an elaborate and valuable roport upon 
the action of acids, alkalies, carbonic acid, 
tetanization and temperature upon electro- 
tonic currents in nerve. Such currents are 
physiological, as wellas physical. Normally 
the anodic current (A) is greater than the 
kathodie (K.), in the proportion of 4 or 5 
tol. Rise of temperature to 40° causes 
diminution of A and increase of K. K is 
favored by acidification and tetanization, 
disfavored by basification ; alterations of A 
are less uniform and characteristic. Tetani- 
zation and CO, have similar effects upon the 
electrotonic currents. In Dr. Waller’s 
opinion this proves that the tetanization of 
an isolated nerve gives rise to a production 
of CO,. In view of the impossibility here- 
tofore of obtaining any evidence whatever of 
metabolism in an acting nerve, this conclu- 
sion is most important and suggestive, as 
SCIENCE. 
LN. S. Vou. VI. No. 145. 
bearing upon the nature of the nerve im- 
pulse. During the presentation of Dr. Wal-_ 
ler’s paper Miss Welby demonstrated the 
method used in his laboratory of applying 
anesthetics to isolated tissues, employing 
for the purpose cardiac muscle. Professor 
Charles Richet (Paris)-announced his dis- 
covery ofa refractory period in the cerebral ~ 
and medullary nervous centers of the dog. If 
these be rhythmically stimulated they will 
respond to either every stimulus or only ev- 
ery other one, according to the temperature 
and rate of excitation. The duration of the 
period is 0.1” at 30° C. Man has a refractory 
period, since he cannot think ata greater 
frequency than 10 to 12 per second. Hence 
the psychological unit of time, or the ele- 
mentary period of consciousness, is about 
0.1”, which, therefore, represents the dura- 
tion of vibration of the nerve-center. 
Monday afternoon was given up to dem- 
onstrations. Professor W. P. Lombard 
(Michigan) showed a cheap and simple 
chronograph. Professor C. S. Sherrington 
(Liverpool) demonstrated various new facts 
regarding visual contrast and flicker. Pro- 
fessor A. B. Macallum (Toronto) showed 
microscopic specimens illustrating the dis- 
tribution of iron in cells, and Professors 
W. A. Herdman and R. Boyce (Liverpool) 
microscopic specimens illustrating the pres- 
ence of copper in cells. 
On Tuesday morning the Sections in 
Physiology and Botany held a combined 
meeting to discuss the chemistry and struc- 
ture of the cell. This attracted a consider- 
able audience and was one of the most in- 
teresting of the sessions. The discussion 
was opened by Professor R. Meldola (Lon- 
don), who spoke on the rationale of chem- 
ical synthesis. Comments were made by 
Professors J. R. Green (Cambridge), W. D. 
Halliburton (London), I. Remsen (Johns 
Hopkins), H. Marshall Ward (Cambridge), 
and H. HK. Armstrong (London). Professor 
J. R. Green (Cambridge) presented experi- 
