612 
the method of Golgi did, or rather is doing. 
Where gold failed silver has succeeded, and 
is succeeding. Thanks to the black tract 
which silver when handled in a certain way 
leaves behind it in the animal body, as in- 
deed it does elsewhere, we can now trace 
out, within the central nervous system, the 
pathway afforded by the nerve cell and the 
nerve cell alone. We see its dendrites 
branching out in various directions, each 
alert to dance the molecular dance assigned 
to it at once by the more lasting conditions 
which we call structural, and the more pass- 
ing ones which we call functional, so soon 
as some partner touch its hand. We see 
the body of the cell with its dominant nu- 
cleus ready to obey and yet to marshal and 
command the figure so started. We see 
the neuraxon prepared to carry that figure 
along itself, it may be to far-distant parts, 
it may be to near ones, or to divert italong 
collaterals, it may be many, or it may be 
few, or to spread out at once among numer- 
ous seemingly equipollent branches. And 
whether it prove ultimately true or no that 
the figure of the dancing molecules sweeps 
always onwards along the dendrites towards 
the nucleus, and always outwards away 
from the nucleus along the neuraxon, or 
whatever way in the end be shown to be 
the exact differences in nature and action 
between the dendrites and the neuraxon, 
this at least seems sure, that cell plays upon 
cell only by such a kind of contact as seems 
to afford an opportunity for change in the 
figure of the dance, that is to say, in the 
nature of the impulse, and that in at least 
the ordinary play it is the terminal of the 
neuraxon (either of the main core or a col- 
lateral) of one cell which touches with a 
vibrating touch the dendrite or the body of 
some other cell. We can thus, I say, by 
the almost magic use of a silver token—I 
say magic use, for he who for the first time 
is shown a Golgi preparation is amazed to 
learn that it is such a sprawling thing as he 
SCIENCE. 
[N. 8. Vou. VI. No. 147. 
sees before him which teaches so much, and 
yet when he comes to use it acquires daily 
increased confidence in its worth—it is by 
the use of such a silver token that we have 
been able to unravel so much of the intri- 
cate tangle of the possible paths of nervous 
impulses. By themselves, the acquisition 
of a set of pictures of such black lines 
would be of little value. But, and this I 
venture to think is the important point, to 
a most remarkable extent, and with note- 
worthy rapidity, the histological results 
thus arrived at, aided by analogous results 
reached by the degeneration method, espe- 
cially by the newer method of Marchi, have 
confirmed or at times extended and cor- 
rected the teachings of experimental inves- 
tigation and clinical observation. It is 
this which gives strength to our present 
position; we are attacking our problems 
along two independent lines. On the one 
hand we are tracing out anatomical paths, 
and laying bare the joints of histological 
machinery ; on the other hand, beginning 
with the phenomena, and analyzing the 
manifestations of disorder, whether of our 
own making or no, as well as of order, we 
are striving to delineate the machinery by 
help of its action. When the results of 
the two methods coincide, we may be con- 
fident that we are on the road of all truth ; 
when they disagree, the very disagreement: 
serves as the starting-point for fresh in- 
quiries along the one line or the other. 
Fruitful as have been the labors of the 
past dozen years, we may rightly consider 
them as but the earnest of that which is to 
come; and those of us who are far down 
on the slope of life may wistfully lool for- 
ward to the next meeting of the Associa- 
tion on these Western shores, wondering 
what marvels will then be told. 
Physiology, even in the narrower sense 
to which, by emphasis on the wavering 
barrier which parts the animal from the 
plant, it is restricted in this Section, deals 
