Feb. 10, 1870] 
NEAT RE 
393 
observations. The negroes imported into the Sultan’s domi- 
_ nions come from the countries situated on the higher basin of 
the Nile; and though that valley is the route followed by the 
_ cargoes of slaves on their way to the markets, numbers of second- 
ary channels exist, through which slave-dealers convey their mer- 
chandise. The causes of the supply are the feuds of the negro 
races, the causes of demand are that slavery is inherent in the 
religious system of Mussulman nations, inherent in their social 
system and congenial to their ideas and manners. The author 
considered that Sir Samuel Baker’s expedition to put a stop to 
the slave trade must end in failure; and he quoted the speech of 
Lord Houghton plainly avowing the disappointment felt by his 
friend Sir Samuel Baker on seeing the Mussulmans hostile to his 
'scheme. In conclusion, the author said that, if the Sultan and 
Khédiye really intend doing away with slavery, they have nothing 
else to do but to open wide the gates of their harems. 
DUBLIN 
Natural History Society, February 2.—Mr. R. P. Wil- 
liams in the chair, Dr. A. W. Foot exhibited a young bitch 
terrier suffering from goitre and made a few remarks on the 
subject of goitre in animals. The list of animals affected with 
_this complaint includes the lion, hyzena, racoon, monkey, cat, 
dog, horse, mule, pig, cow, sheep and mouse. The geological 
conditions which appear to be connected with the occurrence of 
this disorder in animals were discussed and commented upon. 
—Prof. Macalister read a paper ‘‘ On some points in the anatomy 
of the sartorius muscle.” —Dr. A. W. Foot exhibited thirteen 
species of dragon flies, collected during the past summer in the 
county of Wicklow: Agrion elesans, minium, piclla, cyathigerum ; 
Lestes nympha, Calypteryx virgo, splendens, ischna pratensis, 
nincea, grandis, Libellula quadrimaculata, striolata and caru- 
lescens. 
MANCHESTER 
Literary and Philosophical Society, January 25—J. P. 
Joule, LL.D., F.R.S., &c., president, in the chair. 
“On organic matter in the air.” By Dr. R. Angus Smith, 
F.R.S., &c. In referring to the new experiments by Prof. 
Tyndall on this subject, the author mentioned that he had long 
ago proved the existence not only of inorganic and organic mate- 
rial; but also of organised bodies in the atmosphere. He did not 
claim to have originated the idea that this is the case; but rather 
to have furnished proof and quantitative demonstration of the 
- fact, as far back as 1846, when he brought a notice of the subject 
before the Chemical Society and, in 1848, in a report to the 
British Association ; having also followed up the inquiry since 
then, in conjunction with Mr. Dancer and published his results 
at various times. In conclusion he says we must not be panic- 
stricken because of the presence of organised germs in the air. 
Some are hurtful; but it may be that others are required for the 
maintenance of healthy animal life exactly as in vegetable fer- 
mentation. 
Prof. Williamson exhibited some specimens affording addi- 
_ tional information as to the organisation of calamites. Through 
Mr. Butterworth he had succeeded in obtaining examples whose 
structure was intermediate between calamodendron and cala- 
_mopitus. In the general arrangement of separate parts the new 
specimens corresponded closely with the type figured by Mr. 
Binney; but they differ in two important particulars. All the 
- fibro-vascular tissues are of the reticulate type seen in calamo- 
pitus and dictyoxylon, with a few scalariform vessels here and 
there. The cellular lamine separating the vascular wedges exhibit 
remarkable variations eyen in the same specimen; the cells being 
sometimes elongated into vertical forms of prodenchyma—some- 
times extended transversely and still more frequently they con- 
sist of ordinary parenchyma. In some the fibro-vascular tissues 
of the wedges are separated by masses of cellular tissue, both at 
the nodes and internodes. These tissues, or modified medullary 
rays, are so numerous in one example, that more than two 
vertical vessels can scarcely be found in contact without the inter- 
vention of one of these vertical rows of mural cellular tissue. In 
other specimens these medullary rays are much more scanty, as 
if connecting the type under consideration with that figured by 
Mr. Binney. In these new examples, the verticillate medullary 
radii of calamopitus are wholly wanting. Additional proof is 
thus afforded that all three of the types may be only variations 
of the common calamodendron and it thus becomes more 
demonstrable that in the Lancashire coal-field, at least, we have 
no evidence of the existence of an equisetiform type of calamite 
distinct from the calamodendroid one, The author further 
announced the discovery by Mr. Butterworth of a young cala- 
mite in which the vertical layer is well preserved, presenting a 
parenchyma of somewhat remarkable structure and of a thick- 
ness equal to the ligneous zone which it invests. Its further 
description will be given after investigation. 
**On the so-called molecular movements of microscopic par- 
ticles.” By Professor Stanley Jevons, M.A. In studying the pheno- 
menon first pointed out by Robert Brown in 1827, the author 
found that silicates appeared to be generally the most active sub- 
stances in this respect, pure quartz crystal in fine powder maintain- 
ing rapid oscillation: but charcoal, red phosphorus, antimony 
and sulphur were also very active. Metallic oxides and earthy salts, 
such as carbonate of lime, appeared to be less active ; but it can- 
not be said any substance is free from such motion. On varying 
the liquid, however, by dissolving salts in it, the fact became 
apparent that pure distilled water gave rise to the greatest 
activity. The motion appeared to be closely connected with the 
suspension of fine powder in water, a fact already noticed by 
Dujardin.* All acids, alkalis, or salts which checked the motion 
were found to facilitate the subsidence of suspended material, 
Gum arabic, on the contrary, prevents subsidence and it has a 
remarkable power of exciting the molecular motion. The author 
was soon convinced that the motion was due to electrical action, 
by the close analogy with the circumstances under which electri- 
city is produced by the hydro-electric machine, pure water alone 
producing much electricity, while almost any salt, acid, or alkali 
prevented the action by rendering the watera conductor. Am- 
monia, however, is a remarkable exception in this respect and it 
does not stop the molecular motion or tacilitate subsidence of 
suspended material. Boracic acid, likewise, is a non-conductor 
and does not cause subsidence. 
However, acetic acid, which Faraday stated did not render 
water a conductor, does, in common with other vegetable acids, 
occasion subsidence. It is probable that silicic acid does not 
render water a conductor, since silicate of soda tends to increase 
the molecular motion rather than otherwise and this is another 
exception to the general influence of soluble substances in causing 
subsidence. 
The author is of opinion that this motion of suspended par- 
ticles is closely connected with the phenomena of osmose as a 
case of action and reaction ; for, if a liquid be capable of im- 
pelling a particle in a given direction, the particle, if fixed, would 
be capable of impelling the liquid in an opposite direction with 
an equal force. The earthenware jars used by Graham were 
composed of a substance highly active under the microscope, 
and the fact that osmose is chiefly an affair of very dilute solu- 
lutions, certainly accords with the electric origin of the molecular 
motion, which the author considered to be established experi- 
mentally, pointing to the experiments of Wiedemann on electric 
osmose as suggesting a speculative explanation. Solid particles 
of organic substances also exhibit the motion ; albumen, distrin, 
sugar, starch-solution, alcohol, &c., have little power to arrest 
the motion. The author thinks it not unlikely that, when these 
phenomena are fully investigated, they will give strong support to 
the theory lately put forward by Becquerel, that the movements 
of liquids in animals and plants are really due to electric action. 
Mr. Dancer stated that particles approaching to a spherical form 
showed the greatest activity with some few exceptions, as in the 
case of sublimed mercury and sulphur. He did not regard 
electric action as a satisfactory explanation of the phenomenon, 
and thought the results of many experiments pointed to heat as 
a probable cause. —* On a general system of numerically definite 
reasoning,” by Prof. W. Stanley Jevons, M.A. The substance 
of this paper was given in the report of the Royal Society's 
proceedings for January 20, 
LIVERPOOL 
Naturalists’ Field Club, January 14.—The Rev. H. I. 
Higgins, president, in the chair. The President informed the 
members that Mr. H. S. Fisher was in communication with some 
botanists in the south of England, with the view of obtaining 
exchanges of specially local plants and that he had been successful 
in supplying a gentleman in Cornwall with fifty or sixty specimens 
of plants, placed in a list of desiderata forwarded by him—among 
them Centaurea latifolia—a plant peculiar to Crosby in this 
neighbourhood. He also mentioned that he had witnessed the 
phenomenon known as the Zodiacal Light at Rainhill on the 
19th of December last, at 4.25 P.M. In substance, but not in 
form, it resembled the tail of a comet.—Mr. Gibson then read a 
* Manuel Complet de l’Observateur au Microscope. Paris; 1843, p. Go, 
