Imágenes de páginas

modified by this scientist's own observations, M. Prevost found that the cord of the tympanum is not entirely lost in the lower maxillary gland, but sends threads to the tongue. Employing the Waller method, he divided the tympanum-cord of dogs, cats, &c., and a few days after found wasted nervous tubes in the terminal branches of the lingual.

M. Prevost has given as the results of some experiments upon the nerves of taste. These are opposed to the hypothesis that the fibers, of the lingual nerve which transmits the gustatory impressions, pass through the spheno-palatine ganglion. In fact, the amputation of two spheno-palatine ganglions, accompanied by the section of the two glossopharyngeal nerves, does not alter the transmission of the gustatory sen. sations in the parts moved by the lingual nerve.

Under the head of physiology should also be mentioned a communi. cation concerning the investigations of the congress of medical men at Lyons, in regard to the supposed cause of the fevers which justly give to the climate of the Dombes a character for insalubrity. In this com: munication the intermittent fever of these regions is attributed to the spores of a conferva, very abundant in the marshes of that neighborhood, which rise in the air, with the water evaporated.

M. Lombard, in regard to a subject upon which he had before ad. dressed the society, presented the fact that pulmonary consumption or phthisis decreases with altitude, and mentioned Davos station, at an elevation of 1,556 meters, as having been found particularly favorable to persons affected with this disease.

In natural history proper, M. V. Fatio has given an account of his researches in regard to the development of the black salamander, which differs greatly from that of the spotted variety. The black salamander produces only two living progeny, although at the same time the ovary contains a large number of eggs. Four of these eggs are developed at the expense of the others, which are decomposed and serve them as nourishment; after a time the development of two of the four embryos is arrested, and they in turn serve as nutrition for the last two, which alone survive, and are born after undergoing various metamorphoses.

M. Lombard exhibited to the society a blind fish from the Mammoth Care of Kentucky, sent to the Museum of Geneva by M. V. Lombard.

Vegetable physiology has been represented, first, by a communication from M. Rissler, upon the nutrition of plants. M. Rissler reminded the society that he had before presented some researches upon the double part played by the humus, which assists the dissolution of the mineral substances useful to the plant, and also furnishes a portion of the car. bon it contains. His views were opposed to a subsequent memoir upon the same subject, to which he drew attention, by M. Grandeau, in which M. Rissler's researches are not mentioned, and according to which the part played by the humus consists only in dissolving the nutritive substances.

M. de Candolle, in noticing the appearance, recently observed, of Algerine plants in France, expressed his doubts as to their definite estab. lishment, and gave some examples of exceptional and temporary devel. opment of plants.

While exhibiting to the society a flower of the orchid order, the An. græcum sesquipedale, a plant which is a pative of Madagascar and only very recently introduced into Europe, M. E. Boissier gave us the views of Darwin in regard to the mode of fecundation of this flower. It is remarkable for a spur of extraordinary length, the elongation of which Darwin considers must be the consequence of the length of the proboscis of a certain butterfly which is still unknown, and which would be the only insect which could determine the fecundation of this orchid. In fact, in all the flowers provided with short spurs, as this butterfly touches the nectar with the end of its proboscis, and does not introduce the latter entirely, it does not carry off pollen with its head. Such flowers, in consequence, do not participate in the fecundation of the others, and tend to disappear. M. Boissier made some objections to this theory, which he considers insufficiently founded upon observation and eren logical deduction.

M. Müller claimed to have proved in a striking manner the intimate mingling of the two distinct forms of the ordinary cowslip or primrose, and gave this fact as a remarkable example of dimorphism. He recalled to mind that if fecundation takes place under the most favorable conditions, it must be between flowers of opposite form.

A communication was made to us by M. Lichtenstein, of Montpellier, upon the ravages caused in vineyards by the Phylloxera vastatrix. In the same family of plants certain species seem to be spared by this disease. Thus, although the European vine transported to America may be affected by it, it does not attack the vine indigenous to America. M. Lichtenstein has not observed in Switzerland the injurious species of Phylloxera.

Lichens, and the theory of M. Schwandener, according to which they have been assimilated to a combination of mushrooms and sea-weeds, have been the subject of a communication from M. Müller. It is true that the anatomic structure of lichens exbibits the superposition of green cells called gonidés, and this is analogous to that of sea-weeds, also a ielty tissue containing no chlorophyl, in which it resembles the organization of mushrooms; but still we never find among the lichens the effects produced by the parasitism of the mushrooms, and there exist among them forms of fruit and spores never found among the mushrooms. M. Müller does not accept this theory, and sees in lichens a dimorphism of which the two terms are: 1. A complete state, known under the name lichen. 2. An incomplete state, never producing fruit, and wbich corresponds to the lichen which grows in an isolated condition.

M. Duby informed the society that an anomalous moss had been sent to him from New Caledonia. He described two characteristics found in no other known inoss, which establishes a new genus. The name Mr.

Duby has given to this genus is Sunodontea, and the species has been called Spathoidea.

M. de Candolle has stated to the society that a plant, the Linnea borealis, whose existence in our vicinity has been unkuown since De Saussure found it growing upon the Voirons, had been discovered by M. P. Privat, upon the pass of Oche.

M. W. Barbey presented to the society an article upon plants of the genus Epilobium. In this genus there are some especial difficulties in the determination of species, concerning which there is great uncertainty, notwithstanding numerous investigations. The seed ought to furnish the best characteristics for determination, but the Epilobia mul tiply readily by suckers, which favors the permanence of the hybrid specimens which abound in this genus. These plants are found in great abundance in New Zealand.

M. Humbert has presented several very interesting communications upon some publications relative to natural history, particularly upon the work of Hæckel on calcareous sponges.

I ought also to mention several reviews, presented by different members, of published works; among others, that of M. Ernest Favre, of the work of M. Barrande upon the silurian formation of Bohemia, and those of M. Micheli, of the new edition of the treatise on botany of M. Sachs, and of a work of M. Krauss, professor of botany at Erlangen, upon the coloring matter of chlorophyl.

If I do not dwell upon communications of this kind, it is because, in the reports of the president, as I have said before, it is customary to confine attention principally to original papers; but I cannot terminate this report without special notice of the communication, so full of interest, made by M. Alphonse de Candolle to the society, in its session of June, 1873, the last at which I had the honor to preside. In announcing the publication of the seventeenth and last volume of the Prodromue systematis naturalis regni vegetabilis, he gave an historical summary of this great and important work. I willingly extend this detailed account of what I consider one of the most glorious memorials of the science of Geneva.

The idea of making a complete revision of the vegetable kingdom was conceived by Augustin Pyramus de Candolle, during the last years of his residence in Montpellier, about 1813 or 1814.

The end he proposed to himself then, especially, was to improve and diffuse the knowledge of the natural system he was the first to make use of, in an important flora, (Flore française, 1805,) and the principles of wbich he unfolded in his elementary treatise, (1813.) He began with some monographs of families, very carefully elaborated, which he published in two volumes called Regni vegetabilis systema naturale, (1818 and 1821.) He soon saw that to treat every family in this way would be beyond the powers of one man, and would require a great deal too much time, even supposing, as was then believed, that the number of species did not exceed 25,000 or 30,000. De Capdolle modified his plan, and took up the series of families under a very much abridged form in his work which he called the Prodromus. The title indicates that he at some future time hoped to take up again the Systema, but the enormous iu. crease in the number of species discovered, after the peace of 1815, soon convinced him that this was impossible, and as the articles in the Prodromus were considered too brief, he lengthened the descriptious, after the third volume, and continued to do so until the middle of the seventh volume. There he came to the end of the great family of compound flowers, the elaboration of which was his last and greatest effort.

He was attacked by a serious illness just as he attained his sixtieth year, and was obliged to accept of assistance in the work of continuing the Prodromus, which he had never before done, except with articles of very little consequence. MM. Bentham, Dunal, Decaisne, Grisebach, Choisy, Duby, Boissier, Moquin, Meissner, and Alphonse de Candolle contributed their aid, and gradually furnished extended articles. De Candolle expired on the 9th of September, 1841, and his son continued to direct the Prodromus, preparing himself certain articles. With the aid of other assistants, at the end of thirty-two years he had added ten volumes to the seven that his father had published. The seventeenth volume completed the principal class of the vegetable kingdom, the Dicotyledons, with the exception of .one family (Artocarpeis) which the author could not prepare in time, notwithstanding the delay accorded him. The whole forms a series of unparalleled monographs, including 214 families, 5,134 genera, and 58,975 species.

The Prodromus has been, we may say, the great authority of descriptive botany for half a century. Its order for families has generally been adopted, its form of compilation imitated, and what it proposes or sanctions admitted. It has been of great service in doing away with a number of gevera and species for which there was no foundation. As the work was published when most of the new plants were discovered, it contributed greatly to making them known. It includes 657 new genera and 11,790 new species; that is to say, more than Linnæus kuew of for the whole vegetable kingdom. M. de Candolle shows, by comparing the volumes three by three from the commencement of the work, that tbe proportion of new genera in relation to the old constantly diminishes, while the proportion of new species remains the same; that is always about 25 per cent. We may, therefore, conclude that by the end of the present century we shall have discovered very nearly all the genera which exist, while with species this is still far from being the case.

One of the causes of the influence of the Prodromus has been its entire impartiality with respect to the botanists of all countries. The authors have been chosen without reference to nationality. They are tbirty-three in number, including MM. Candolle, and of these thirtythree contributors twelve are Swiss, nine Srench, seven German, three English, one Italian, one Swedish, one from Holland, and one a Belgian.

Augustin Pyramus de Candolle has written almost a third of the work, 4,303 pages; Alph. de Candolle, 1,387 pages; J. Müller, of Argovie, 1,144; Bentham, 1,133; Meissner, 835; Dunal, 732; the twentynine other assistants, articles less extended. De Candolle, his son, and his grandson (Casimir) have compiled 5,917 pages out of the whole 13,194. The contributors residing at Geneva have furnished six-tenths.

The mere correction of proof in such an especial work has been a great labor for the two directors, who have done it all themselves. They have also greatly assisted their colaborers, by taking notes for sixty years, without interruption, of all new descriptions and plates which have appeared in botanical books and journals. These notes, classed by families, form the most complete repertory of descriptive botanical literature ever compiled.

Several motives induced M. de Candolle not to extend the Prodromus beyond the Dicotyledons. The principal one was the great increase in the difficulty of the work, on account of the continually-increasing number of specimens to be examined and of species and characteristics to be determined by the aid of the magnifying-glass. When A. P. de Candolle commenced, an active botanist could describe, according to the custom of the time, 1,500 or 1,800 species a year. Now, with the work prepared as in the last volumes of the Prodromus, and in accordance with the existing state of science, an industrious botanist could describe not more than 300 or 400 species a year. The difficulty of obtaining the manuscripts at the time promised by the authors was another great obstacle. To this cause must be attributed the delay in the publication of the Prodromus, the volumes having appeared more and more slowly in proportion as the number of writers was increased.

The execution of this magnificent work has required fifty years, indeed sixty, if we go back to its origin. It has employed three generations of the same family, which is an unusual circuinstance in the history of science, and will forever associate the name of Candolle with the most remarkable scientific achievements of Geneva.

« AnteriorContinuar »