TRANSACTIONS OF THE SECTIONS. 135 
changes described by Kélliker in the spleen will take place, and that, although from 
the frequency of these conditions in that organ the changes in question may be more 
frequently seen in it than in other structures, these changes bear no relation to the 
most important part of the function of the organ, viz. that which is performed by the 
constituent cells. 
4th. That none of the cellular elements of the spleen are set free and normally 
enter the circulation as such. 
On a Physiological Mode of resolving the Metaphysical Difficulties as to the 
Origin of the Notion of Space, of Motion, of the External, of Substance, 
$e. By Witt Setter, M.D., F.R.S.E., President of the Royal Col- 
lege of Physicians of Edinburgh. 
The purpose of Dr. Seller’s paper was to show that the metaphysical difficulties, 
as to the origin of the notions of space, of motion, of the external, of substance, &c., 
might be resolved physiologically on the: two axioms, “that every sentient nervous 
filament is an independent instrument of sensation, and that every sensation involves 
an element of space, namely, the. point of space where the organic change produced 
by the impression originates, thaf is, at the peripheral extremity of the nervous fila~ 
ment concerned ;”’ that the infant thus comes to recognize the relative position of 
all the sentient points in the space occupied by the skin and muscular system, and 
that out of the element of motion besides involved in the sensation attendant on the 
contraction of every portion of muscular substance supplied with a sentient nervous 
filament, he finally comes to recognize the external contact of one part with another 
of the zone of space occupied by self, and the resistance of one part of self to the in- 
trusion of another part of self; and that, having at length acquired the knowledge of 
the properties of the body itself as a piece of matter, he quickly obtains the notion of 
the external, because when an external body is touched it is distinguished bf the ne- 
-gative property of affording no consciousness of being touched like that afforded by 
every part of self. The whole of the paper was not read, and therefore the entire 
view was not brought out. 
On the Causes which advance or retard the appearance of First Menstruation 
in Woman, with a Synoptical Table showing the Mean Age of First Men- 
struation in 10,422 Women in Hot, Temperate, and Cold Climates, 
By E. J. Τα, M_D., Senior Physician to the Paddington Free Dispensary 
for Diseases of Women and Children, and Physician to the Farringdon 
General Dispensary and Lying-in Charity. 
Whatever bears upon the theory of population is more than ever interesting, seeing 
that certain portions of the globe having become too densely populated, we are seeking 
to draught the overplus to far distant climes, to those wildernesses which have but 
seldom echoed the voice of man. 
To ascertain the period of first menstruation in any variety of the human race, is 
to ascertain when its reproductivity becomes possible, a matter equally interesting to 
the physician, the philosopher, and the statesman; and it behoves them to know that 
this epoch varies under the influence of causes which for the most part have been 
insufficiently studied. 
Dr. Tilt divides the modifying influences of the first establishment of menstruation 
into— . 
I. The extrinsic causes, such as climate, habitation, civilization. 
II, The intrinsic causes, such as race, family, and national customs. 
Dr. Tilt is of opinion that the action of the extrinsic causes is indubitable ; and in 
proof of the influence of the first and most important cause, that of climate, he ad- 
duces the following carefully-made table, in which he has brought in striking oppo- 
sition to such cases as we have been able to obtain from India, 3840 obtained from 
Denmark, and now for the first time made public; the sixteenth year in Denmark, 
the thirteenth in India, and the fourteenth in temperate climates, being the epoch at 
which this function generally begins. x 
