of assimilation? If the disruption of carbonic dioxide within the cell furnishes oxygen directly, how can any assimilating cell suffer from want of oxygen? Pringsheim does not admit the usual assumption italicized above. His opinion is that the analysis of the CO, in assimilation does not directly furnish oxygen, but that some other substance is formed, which, passing diosmotically to the surface, breaks up and liberates free oxygen. He criticises the usual arguments based on the results of gas analysis. What the substance is which forms oxygen at the surface he is not prepared to state. If this be so, the breaking up of CO2 and the liberation of O are two processes, distinct both in space and time, the one occurring within the cell, the other at its surface. This view is supported by reference to the peculiar liberation of oxygen exhibited in darkness by both green and unpigmented cells toward death. The bacterium-method proves this fact incontestably. This liberation of oxygen in darkness, quite independent of contemporaneous assimilation, may be termed "intramolecular liberation of oxygen," and, according to Pringsheim, the normal liberation is an essentially similar process, resulting from the disruption of an exosmosing substance. He advances other arguments to show that we are not warranted in concluding, as has hitherto been done, that the presence of light, chlorophyll and CO2 exhausts the conditions of assimilation, and that in estimating its amount no other factors but light-energy and the absorption of light by the chlorophyll have to be taken into account. Assimilation is, on the contrary, a physiological function of the protoplasm, and, like movement, depends on the presence of free oxygen. Physiologists will look with interest for Pringsheim's detailed account of his investigations on this important subject. The proposed Botanical Exchange Club.-The committee appointed by the Botanical Club of the A. A. A. S. at the New York meeting to act for the club in the formation of a Botanical Exchange, after considerable correspondence and the consultation of the rules and regulations of similar organizations abroad, is now in a position to submit to the members of the club certain tentative propositions, on which individual opinion is solicited. The regulations of the Botanical Exchange Club of the British Isles, published in pamphlet form at Manchester in 1886, seem applicable to our needs, with certain necessary modifications. In order to bring these before the botanists of the country, a synopsis of them is here presented, arranged with reference to America instead of Great Britain. 1. The object of the club will be to facilitate the exchange of herbarium specimens of American plants, specially of rare species and varieties. The conditions of membership to be that each member shall furnish a parcel of specimens annually, and pay a yearly subscription of a sum not to exceed ($3.00) three dollars, to meet the expenses. Members will be entitled to a share in the distribution of specimens made in the early part of the year following that in which their subscriptions and parcels were sent. 2. The annual list of desiderata will be made up by combining those of all the members of the club, and then be printed and sent to every member. Each individual list must not exceed a certain number of species annually, for if unlimited the printed list would be too voluminous for practical use with our very extensive flora, at any rate for a number of years. The determination of the annual number of desiderata will require further consideration. 3. Some member will have to act as distributor each year, either voluntarily, or. if no one is found willing to act without recompense, provision will have to be made for employing a distributor at a small salary. The plan as here outlined would not necessitate very much work, and it certainly would be of an interesting nature. The committee will be pleased to receive communications relative to this.' 4 It will be necessary to adopt some one check-list as the official one of the club, and this must either be used in sending lists of desiderata by marking the species desired, or if a reliable numbered check list can be procured, the list of numbers might be sent. This is also a question for further consideration. It has been the experience of the British Club that manuscript lists of desiderata should not be received. 5. Each species should be represented by a number of specimens to be determined when the probable number of members shall be ascertained. It is not necessary to emphasize at this time the necessity for complete and satisfactory specimens being furnished, with appropriate labels. The British Club in 1886 had a membership of fifty-eight, and has been in successful operation for a number of years. It would seem certain that at least an equal number of American botanists would consider it advantageous to join a similar organization. Suggestions regarding the matter here presented and applications for membership should be sent to the chairman of the committee, Dr. George Vasey, U. S. Department of Agriculture, Washington, D. C. THE COMMITTEE. Phacelia heterosperma. —Annual, a foot or less high, with erect branches, glandular and viscid, the foliage and inflorescence with sparse short and viscid hairs: leaves few on short petioles, ovate, an inch lɔng, with a few coarse angular teeth, or the basal ones nearly entire flowers in strict spiciform racemes, at length elongated and loose: corolla com Dr. Vasey writes that Commissioner Colman has consented, if it be deemed advisable, that the Botanical Division of the Department of Agriculture take charge of the exchanges. and distribution without expense to the members of the club. N. L. B. panulate, 3-4 lines high, little exceeding the spatulate sepals, light purple with yellowish base: the unequal filaments and short cleft style included capsule oblong, 3 lines high, exceeded by the sepals; seeds numerous (40-50), light brown, deeply pitted and variously angled or rounded. Of the Eutoca group.-In wet sand, banks of Rock creek, borders of the Mojave desert, Los Angeles Co., Calif., June, 1887.-SAM'L B. PARISH, San Bernardino, Calif. EDITORIAL. THE DEATH Of Dr. Asa Gray removes from American botany one who can have no successor. His work may be continued, but his commanding position can not be attained by any other. The circumstances which gave him such a grasp upon men and materials will not be repeated. The greatest name in American botany is the unanimous verdict of his countrymen. But his most enduring monument is not this unanimous acknowledgment of his greatness as a botanist, but the loving remembrance of the kindly, helpful man, which is cherished in the hearts of more than one generation of botanists, none of whom he ever turned away unanswered, all of whom he considered as friends that must be helped. Two years ago the GAZETTE published, with his sanction and help, a biographical sketch; and it but remains now for us to pay our tribute of love and respect to one who has been taken away, full of years and honor, but still in the midst of his work. The loss seems an irreparable one, but his name will always be a guide and incentive to every American botanist THE ARTICLE by Dr. Minot in a recent number of Science regarding the unsuitableness of American microscopes for the use of biologists has provoked comment from nearly every American journal dealing wholly or in part with biology, and the verdict appears to be that some of the writer's points were well taken, although the statements may have been stronger than the facts will warrant. The rapid increase in number and size of biological laboratories brings about an increasing demand for a low-priced instrument adapted to certain kinds of work. This demand is met by German manufacturers, but is to a certain extent ignored by American manufacturers. The result is that probably half of the instruments now bought for biological purposes come from abroad, and the number would doubtless be greater but for the trouble and delay of importing. The subject is one that has often been discussed, but the present agitation is more general than at any previous time, and promises to be more fruitful, as it has aroused the makers to a show of defense. The American manufacturer takes pride in the handsome instrument which he turns out, and the only influence that is likely to be strong enough to develop a permanent interest in the small plain instrument the biologist is asking for is a financial one. That there is an inclination to meet the rising demand is evident from the circular of inquiry sent out by Queen & Co. last year, from the construction of the" Harvard" stand by Bausch & Lomb Optical Co., which embraces some features of the foreign models, from the similar stand just put in the market by Bulloch, and from the tone of the replies already made to Dr. Minot's article. The old prejudice against American instruments, because American, has nearly passed away, and the investigator is now likely to buy where he can best and most easily meet his needs. On the other hand, if the instrument-maker will lay aside his prejudices against a plain instrument of superior workmanship, there will not long be grounds for accusation and controversy. OPEN LETTERS. Mutilation of flowers by insects. On page 111, 1887, of the GAZETTE I suggested that botanists note all cases in which insects mutilate flowers for the purpose of securing the nectar; and that the insects be captured, and their scientific names be published with such notes. Professional duties have made it impossible for me to give much time to this class of observations, but have the following notes which may be of some value. I found that a majority of the corollas of a large number of plants (examined in several localities) of Physostegia Virginiana and Mertensia Virginica were slitted as described in the GAZETTE for October, 1886 and May, 1887. The only insect which I found doing this work was Bombus Pennsylvanicus. For nearly two months, during the past summer, I had under observation two large vines of two species of honeysuckle. In the first, the common woodbine, the corolla is deeply cleft, with the lips well turned back. This plant is deliciously fragrant, and, to my surprise, the only insects which visited it belong to the genus Halictus, apparently all the same species. All entered at the open mouth of the corolla. The flowers are proterandrous. In the second, the trumpet or coral honey-suckle, the mouth of the corolla is small and the short divisions not reflected. It is also proterandrous. This species was abundantly visited by the leaf-cutter or upholster bee (Megachile brevis), and one or more species of Halictus.' The leaf-cutter bee never enters the mouth of the corolla, but goes directly to the base, and shears out a round piece, usually near one-eighth inch in diameter; through this it extracts the sweets. It is sometimes necessary to make two or three openings before it gets to the right place. This operation is done as easily and quickly as one could do it with sharp scissors. In the majority of instances the piece cut out is allowed to hang by a little hinge at one side. Through this circular opening the Halietus enters and makes a more thorough search for the remaining honey. 1 These small insects are commonly known as "sweat bees," from their habit of alighting on one's person while sweating freely and sucking up the perspiration. Mr. C. M Weed, of the II. State Laboratory, kindly identified the insects for me. In case the flower has not been visited by a Megachile the Halictus goes to the mouth of the corolla and enters in the usual way; but it usually alights on the base first and hunts for the artificial opening. Mt. Carmel, IU. J. SCHENCK. An acknowledgment. In the correcting of the proof of the paper on the ostrich fern, noticed in the GAZETTE for December, a paragraph stating under what conditions the investigations were made was inadvertently omitted. The work was done under the supervision of Professor V. M. Spalding, of the University of Michigan, to whom the author begs to offer this somewhat tardy expression of his thanks for the valuable assistance and encouragement received from him during the pursuance of the work. DOUGLAS H. CAMPBELL. Berlin, Germany. CURRENT LITERATURE. Flowers and fruit of Sparganium and Typha.' In this monograph Dr. Dietz has given the results of a comparative study of the development of the floral and fruit structures of Sparganium and Typha. It is a good model of those studies which are necessary before botanists can speak with any definiteness upon the relationships of plants; studies which should be greatly multiplied, and which furnish a vast and useful field of labor for our ever increasing army of botanists. Taking a group of doubtful relationships, the author has laid the foundation for a rational discussion of the subject, which he promises at some subsequent time. The vegetative structures are mostly alike, but the reproductive organs show notable differences. A radical difference occurs in the positions of the flowers themselves, those of Sparganium occurring upon secondary and tertiary axes, while those of Typha are upon primary and secondary axes. Every detail in the development of the floral parts is described and figured with that minuteness that seems to leave none of the anatomical details unrecorded. The greatest differences are found in the structures of the pistil, the most apparent of which is its bicarpellary character in Sparganium, and monocarpellary character in Typha. The formation of the integuments of the seed also differs widely. In conclusion, the author considers that, while there are enough characters in common to justify retaining these two genera in one order for the present, the differences are sufficient to indicate that there may be ordinal characters. This structural study shows that Sparganium is nearest to the Pandaneæ, while Typha shows relationships to the Aroideæ. 1 DIETZ, DR. SANDOR-Ueber die Entwickelung der Blüthe und Frucht von Sparganium Tourn. und Typha Tourn. (Bibliotheca botanica, heft 5.) 60 pp., 3 plates. 4to. Cassel: Theodor Fischer, 1887.-8 marks. |