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antheridiis 5 - 7 longe pedicellatis; paraphysibus paucis curtis ; foliis perigon. late ovatis recurvo-apiculatis ecostatis sublimbatis. - Hab. Vicinity of Valparaiso, Chili.

“ 23. NECKERA TRICOSTATA (n. sp.): dioica ? majuscula, fusco-lutescens ; caule primario repente radiciformi subterraneo ramos erectos inferne atratos defoliatos superne speciose dendroideo-ramulosos emittente, ramulis elongatis flexuosis simplicibus compositisve dense foliosis fructiferis ; foliis erecto-patentibus incurviusculis e basi lata subtruncata ovato-oblongis acuminatis concavis carinato-costatis, costa valida cum apice desinente, toto ambitu incrassate limbatis veluti tricostatis superne grosse serratis, cellulis compactis minutis subpunctiformibus ; perichætii oblongi foliis arcte imbricatis, inferioribus subsquamæformiorbiculatis, superioribus ad medium erectis oblongo-convolutaceis dehinc subito horizontaliter reflexis tenui-acuminatis, omnibus ecostatis interrupte pellucide sublimbatis ; archegoniis 45 - 50 paraphysibus numerosis fere duplo longioribus 30 - septatis basi interdum composite cellulatis ; cætera desunt. Hab. Forest at the eastern base of Mauna Kea, Hawaii, Sandwich Islands.

“24. RhizoGONIUM PUNGENS (n. sp.): dioicum; cæspite denso hispido e viridi spadiceo; caulibus bi-triuncialibus basi fructiferis erectiusculis simplicibus inferne tomento atropurpureo dense vestitis ; foliis laxiuscule dispositis patenti-divergentibus carinato-concavis semiuncialibus (arista inclusa) strictiusculis rigidis pungentibus elliptico-lanceolatis costa valida subtereti in aristam dorso et lateribus grosse dentatam lamina quintuplo longiorem excurrente instructis basi valde incrassatis e cellulis minutis densis subquadratis compositis, margine duplicatodentato vel potius bilamelloso, lamellis dentatis ; perichætiis radicalibus brevissime stipitatis ; foliis perichætialibus exterioribus lanceolatis dentatis, interioribus oblongis integerrimis, omnibus laxius reticulatis basi vaginantibus costa excurrente valida dentata longissime aristatis ; archegoniis longiusculis numerosis (40 - 50) copiose paraphysatis, paraphysibus 7-10-septatis archegonia paululum superantibus. - Hab. District of Puna, southwest coast of Hawaii, Sandwich Islands."

Professor William B. Rogers called the attention of the meeting to the different explanations which have been given of the two vertical beams of light which are seen stretching, the one upwards and the other downwards, from a luminous VOL. 111.

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point, as the flame of a candle, when we view it with the eyelids nearly closed. He said that until lately he had been accustomed to refer this phenomenon to reflection from the surfaces of the two eyelids, the lower surface reflecting the incident rays upwards through the eye, the upper surface in the opposite direction. From the oblique incidence of the light in each case, the minute irregularities of the surface might be supposed to have the effect, by a linear conjunction of images, of prolonging the picture on the retina, just as the ripples on a lake elongate the image of the moon, or of a burning torch when in a suitable position, so as to form a luminous band stretching over the water from beneath the object nearly to the spectator. A similar explanation has recently been suggested by M. Trouessart in the Comptes Rendus.

The seventh number of Poggendorf's Annalen for the present year contains a paper on this subject by H. Meyer of Leipsic, in which he refers these vertical beams to refraction. As the eyelids are moved over the eyeball, they gather before them the moisture which continually lubricates the surface of the eye. Owing to the oily secretion of the lids, this moisture, instead of spreading on their surface so as to form a concavity outwards, is by the opposite capillarity moulded into a converse form, which may be approximately regarded as a quarter-cylinder lying in the angle of junction of each eyelid with the cornea. The light striking the upper of these convexities will by refraction be bent upwards through the eye, and that incident on the lower will be bent downwards. In this view, therefore, the upper eyelid is the one concerned in producing the beam which appears vertically under the object, and the lower eyelid in producing that which appears vertically over it. But by the hypothesis of reflection the reverse of this must be the case, the beam above the object being due to the action of the upper eyelid, and the opposite beam to the lower eyelid.

Professor Rogers mentioned a simple experiment, which proves that the latter cannot be the true explanation, and which makes it extremely probable that M. Meyer has hit upon the correct one. If, when the eyelids are adjusted so as to develop the two vertical beams in great length and brightness, we cautiously lift away the lower eyelid from the cornea without changing the distance between the two eyelids, we observe that the upper beam instantly disappears; and so, on lifting the upper eyelid, the lower beam vanishes. This is just what ought to happen according to Meyer's view of the origin of the beams. The lifting of the eyelid, by breaking up the convexity of liquid, must of course put a stop to the fan-shaped refraction, and therefore extinguish the vertical beam corresponding to it above or below the luminous object. As the reflection from the surface of the eyelid would be but little altered by the slight removal from the cornea, we ought on the hypothesis of reflection either to find the two vertical beams unaltered, or that beam which is on the same side as the eyelid merely a little feebler and shorter. If, again, we revolve one of the eyelids entirely out of the range of action, while the other is retained in its place, the beam which disappears is found to be for the lower lid the upper beam, and for the upper lid the lower beam, as ought to be the case according to Meyer's explanation. Professor Peirce made a communication on the relations of

SP=0

in which the

Q functions are derived from the equations f (x+y: N-1)= P+QV-1.

Professor Agassiz added some remarks, in which he pointed out some interesting analogies, suggested by Professor Peirce's communication, in certain organic forms in the vegetable and animal kingdoms.

Professor Cooke called the attention of the Academy to . some remarkable relations he had discovered between the atomic weights of the elements; and to some new facts which a knowledge of those relations had led him to observe. He considered the common classification of the elements as not

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founded on correct principles. Disregarding the distinction of metals and metalloids, and guided chiefly, though not exclusively, by the mode of combination and crystalline form, and bringing together those elements which bear the closest relations to each other, he had arranged the elements in six groups, the properties of each of which are closely related to each other, while they differ widely from those of any other group.

The elements of any one group are, for the most part, isomorphous, and from similar compounds. Arranging the elements of any one group according to their relative affinities, and commencing with the strongest, he had found that the physical properties follow the same progression. As in organic chemistry differences of properties correspond to fixed differences of composition, he had noticed that, in like manner, in these series of inorganic chemistry, similar differences manifest themselves in differences of atomic weights. In the series in which he had classified the elements, the differences between the atomic weights of the consecutive members of any one series is always a multiple of some whole number. In one case it is 9, in another 8, in another 6, in another 5, in another 4, and in another 3. He stated that there are some discrepances between the atomic weights, as at present determined, and those required by his theory; and that, though in most cases they are within the limits of actual error, in others there is a residual. These remarks Professor Cooke illustrated very fully by referring to the group consisting of oxygen, nitrogen, phosphorus, arsenic, antimony, and bismuth. He showed that these elements have the same mode of combination; that they not only unite with the same number of atoms, but that the resulting compounds have similar properties, and form parallel series with the elements. He stated reasons for believing that phosphorus, antimony, and arsenic exist in two allotropic states. He had succeeded in crystallizing arsenic in regular octahedrons which belong to a new allotropic state of arsenic ; which in this state differs in color, weight, and chemical properties from common arsenic. He thought there could be little doubt that the members of the nitrogen series are isodimorphs, forming two isomorphous series, one rhombic and the other monometric; and that it was highly probable that the residuals he had noticed in some of the elements might be owing to a difference in the atomic weights of those elements in their two allotropic states.

An interesting discussion followed Professor Cooke's communication, in which Professor W, B. Rogers, Professor H. D. Rogers, and Professor Peirce took part. It was stated by Professor Peirce that the number seven, omitted in the common differences between the atomic weights of the elements, was also omitted in the series of fractions representing the relative distances of the planets from the sun, and the distribution of leaves around the stem of a plant.

Professor Agassiz made a communication on the fundamental law of distribution of organic forms. Further remarks on the same subject were made by Professor H. D. Rogers, in respect to its geological relations; by Dr. Pickering, who described the method he had followed in his researches respecting the distribution of animals; and by Professor Peirce.

Three hundred and ninety-second meeting.

January 10, 1854. – SEMI-MONTHLY MEETING. The PRESIDENT in the chair.

The Corresponding Secretary, by appointment, acted as Recording Secretary, after the reading of the proceedings of the last meeting by J. Hale Abbott, the Secretary pro tem. of that meeting.

Dr. Hayes made a verbal communication on the disappearance of marsh-gas (light carburetted hydrogen) in nature, occurring, as he had ascertained, by its spontaneous combustion, converting it into carbonic acid and water at ordinary temperatures, even at 32° Fahr. He had ascertained the same fact in respect to carbonic oxide also.

Remarks on this communication were made by Professor Cooke and Professor Horsford.

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