278 
NATURE 
| Feb. 2, 1871 

Ist. Its own proper membranous sac ; : 
2nd. Of a posterior part which is acontinuation, in an unseg- 
mented form, of the vertebral column ; , 
3rd. Of lamin which grow upwards from the first pair of 
facial arches, and which enclose the fore part of the membranous 
sac, just as the “investing mass” of the cranial part of the 
notochord invests the hinder part ; ; ; 
3rd. The ear-sacs and the olfactory labyrinth become inextri- 
cably combined with the outer case of the brain. 
And 5th. The subcutaneous tissue of the scalp becomes 
ossified in certain definite patches; these are the cranial roof- 
bones. Around the mouth there are cartilages like those of the 
Lamprey and the Chimera; but these yield in interest to the 
proper facial bars, which are as follows, namely :— 
First pair the “ trabeculz.” 
Second pair the mandibular arch. 
Third pair the hyoid arch. 
And fourth to seven pairs ; these are the branchials. 
These are all originally separate pairs of cartilaginous rods ; 
and from these are developed all the complex structures of the 
mouth, palate, face, and throat. The pterygo-palatine arcade is 
merely a secondary connecting bar developed, after some time, 
between the first and second arches. 
Meckel’s cartilage arises as a segmentary bud from the lower 
part of the second; and the ‘*stylo-cerato-hyal,” as a similar 
secondary segment, from the third arch. ; : 
By far the greater part of the cranium (its anterior two-thirds) 
is developed by out-growing lamine from the trabeculze, which | 
after a time become fused with the posterior or vertebral part of 
the skull. 
When the tadpole is becominga frog, the hyoid arch undergoes 
a truly wonderful amount of metarmophosis. 
The upper part, answering to the hyomandibular of the fish 
(not to the whole of it, but to its upper half), becomes the 
“incus,” and a detached segment becomes the ‘‘orbiculare, 
which wedges itself between the incus and the ‘‘stapes.” The 
stapes is a“ bung” cut out of the ‘‘ear-sac.” The stylo-cerato- 
hyal is set free, rises higher and higher, and then articulates with 
the ‘‘opisthotic” region of the ear-sac ; in the toad it coalesces 
therewith, as in the mammal. The lower part of the hyo- 
mandibular coalesces with the back of the pier of the mandibular 
arch; and the ‘‘symplectic” of the osseous fish appears whilst 
the tadpole is acquiring its limbs and its lungs, and then melts 
again i rch in front ; it is represented, however, in | r resi C 
Deck: aeain anton she age 2 P he. | Veyed to the author the thanks of the society for his interesting 
the Bull-frog, but not in the common species, by a distinct bone. 
This very rough and imperfect abstract must serve at present 
to indicate what has been seen and worked out in this most 
instructive vertebrate. 
‘Modification of Wheatstone’s Bridge to find the Resist- 
ance of a Galvanometer Coil from a Single Deflection of 
its own Needle.” By Professor Sir W. Thomson, F.R.S. 
In any useful arrangement in which a galvanometer and a gal- 
vanie element or battery are connected through whatever trains 
or network of conductors, let the galvanometer and battery be 
interchanged. Another arrangement is obtained which will pro- 
bably be useful for avery different, although reciprocally related, 
object. Hence, as soon as I learned from Mr. Mance his 
admirable method of measuring the internal resistance of a galvanic 
element (that described in the first of his two preceding papers), 
it occurred to me that the reciprocal arrangement would afford a 
means of finding the resistance of a galvanometer coil, from a 
single deflection of its own needle by a galvanic element of un- 
known resistance, ‘Ihe resulting method proves to be of such 
extreme simplicity that it would be incredible that it had not 
occurred to anyone before, were it not that I fail to find any trace 
of it published in books or papers, and that personal inquiries of 
the best informed electricians of this country have shown that in 
this country at least it is a novelty. It consists simply in making 
the zalvanometer coil one of the four conductors of a Wheat- 
stone’s bridge, and adjusting, as usual, to get the zero of current 
when the bridge contact is made ; with only this change of plans, 
that the test of zero is not by a galvanometer in the bridge itself 
showing no deflection ; but by the galvanometer, the resistance 
of whose coil is to be measured, showing an unchanged deflection. 
Neither diagram nor further explanation is necessary to make this 
understood to anyone who knows Wheatstone’s bridge. 
Chemical Society, January 19.—Professcr Odling, F R.S., 
Vice President, in the chair. The following gentlemen were 
elected fellows:—R. Bannister, H. T. Brown, J, Moss, Re 


| parallel of an Algebraical Curve,” by Mr. S. Roberts, M. A. 
J. Moss, E. Potts. The following papers were read :—‘‘ On 
the action of sulphuric acid on the natural alkaloids,” by Henry 
E. Armstrong. On heating narcotine with sulphuric acid, which 
liad previously been diluted by its own volume of water over 
the water-bath, and subsequent addition of ammonia to the 
mixture, a body is obtained which shows at once the properties 
of dimethylnarcotine, the base which Matthiessen and Wright 
had obtained from narcotine by means of hydrochloricacid. The 
reaction takes place, therefore, according to the equation— 
Cyg Hyg NO, +H, S O, = C,, Hy NO, +CH3HS O, 
From this result the author concludes it becomes evident that 
Gerhardt and Laurent’s view, who regarded this body as an 
amide, must be abandoned. On treating codeine in a similar 
manner, and dissolving the base obtained in hydrochloric acid, 
a crystalline hydrochlorate was obtained. Ananalysis of the pro- 
duct showed it to be hydrochlorate of codeine. The first action of 
sulphuric acid results, therefore, in the production ofan isomeric 
codeine. By the further action of sulphuric acid, 1 molecule of 
water is removed from 2 of codeine—then 1 H, O from 1 codeine, 
and finally, apomorphine seems to be formed. On this last point, 
however, further evidence has yet to be awaited. ‘‘On the 
origin of nitrates in potable waters,” by Ch. Ekin. —The author 
found nitric acid in the water of a spring which is very remote 
from any agency that could impart to it decaying animal matter. 
On closer examination, he found that the water in question had 
passed through a fossiliferous stratum. This observation neces- 
sitates a modification of the ‘‘ previous sewage contamination 
theory.”—‘* On an alkaloid from Cinchona bark, hitherto unde- 
scribed,” by Dr. Howard. This new alkaloid was obtained from 
the mother liquors of quinine salts. It is a yellowish oil which 
cannot be sufficiently purified for analytical purposes, The for- 
mula of its platino-chloride corresponds with the formula assigned 
by Gerhardt to the anhydrous platino-chloride of quinine. Mr. 
Macleod exhibited an ingenious little contrivance by means of 
which eudiometer tubes which have lost the outer portion of 
their discharging wires may yet be made use of 
Mathematical Society, January 12.—Mr. W. Spottiswoode, 
F.R.S., President, in the char. The Rev. J. Wolstenholme, 
M.A., Christ’s College, and Mr. R. B. Hayward, M.A., late 
Fellow of St. John’s College, Cambridge, were proposed for 
election. There was a large attendance of members to hear Prof, 
Peirce, of Harvard, give an account of the methods made use 
of in his ‘‘Linear Associative Algebra.” The President con- 
communication. Other papers communicated were ‘‘ On Systems 
of Tangents to place Cubic and Quartic Curves,” by Mr. J. J. 
Walker, M.A., and ‘*On the Order and Singularities of the 
In 
the course of the evening Mr. Roberts stated the following con- 
strection as being mechanically more convenient than one dis- 
cussed in a former paper ‘‘On the Pedals of Conics :”—In a 
| plane, if a limited straight line, whose length is equal to the 
distance between the centre of two equal circles, moves with an 
| extremity on each, the locus of any point rigidly connected with 
the line will consist of acircle, and a bi-circular quartic with a 
third node. 
Entomological Society, January 23.—At the Annual Meet- 
ing this day held, Mr. A. R, Wallace, President, in the chair, 
the following gentlemen are elected to form the Council for 1871. 
—Messrs. Butler, Dunning, Fry, Grut, Higgins, M‘Lachlan, 
Major Parry, Pascoe, E. Saunders, Stainton, 5S. Stevens, A. R, 
Wallace, and Professor Westwood. The following officers for 
1871 were subsequently elected :—President, Mr. A. R. Wallace ; 
Treasurer, Mr. S. Stevens ; Secretaries, Messrs. M‘*Lachlan and 
Grut. Librarian, Mr. Janson. An Address was read by the 
President, which will be published 7 extenso in the Society’s 
Proceedings. 
Ethnological Society, January 24.—Professor Huxley, 
President, in the chair. The Rev. Dr. Steere read a paper 
““On the Tribes and Languages of East Africa.” The author, 
who had resided for several years at Zanzibar, described in 
detail the Swahilis, a mixed race, half negro and half Arab, 
belonging to the Shafi school of Mahommedans. Many examples 
of their folk-lore were introduced, and a detailed description was 
given of the Swahili language. A comparison was instituted 
between the Swahili, Shambala, Yao, and Nyamwezi languages, 
which all belong to the great Baotu family. Mr. Ilyde Clarke 
spoke upon this communication.—A paper was read ‘‘On the 
Weapons and implements used by the Kaffir Tribes and Bushmen — 
