John M. Coulter

Contribution to the Life-History of Ranunculus

IN I896 a group of research students working in the Hull Botanical Laboratory of the University of Chicago began the investigation of a somewhat wide range of spermatophytes. In addition to the individual problems certain representative forms were selected for joint study, among which was Ranunculus. It was felt that a large multiplication of preparations was desirable, in at least a few cases, to discover the possibilities in variation, and this feeling was justified by the result, since very different conclusions could be drawn from different sets of preparations. It is comparatively easy to obtain a definite sequence in the development of structures when the facts are few, but definite sequences seem to disappear as facts multiply. The species of Ranunculus chiefly studied were R. seplentrion7alis, R. multifidus, and R. abortivus, and the results obtained were so constant that it would not be profitable to distinguish in every case among the species in the following account. Certain other genera of Ranunculaceae were examined also, and they contribute to certain conclusions herein set forth.

The Endosperm of Angiosperms

In a recent analysis of all the available testimony in reference to the morphological nature of the endosperm of angiosperms, it seemed clear that certain conclusions might be reached, and the purpose of the present paper is to state them. It has been assumed that the endosperm must be either gametophytic tissue or sporophytic tissue, and the arguments for each view are familiar. The perplexity has arisen chiefly from the feeling that gametophyte and sporophyte must be subject to rigid definition. When definitions become rigid, ideas become rigid also, and nature is always playing havoc with rigidity. If gametophytes and sporophytes are defined as x and 2X structures, respectively, straightway x sporophytes and 2X gametophytes are discovered. If sporophytes are defined as structures produced by fertilized eggs, the definition is contradicted by numerous sporophytes that are not the product of fertilization. In this way, every criterion suggested has found its contradiction. It is becoming evident that definitions must be elastic and not rigid, and that general situations rather than definite categories must determine conclusions. We have moved so far beyond the rigid categories of the days of metamorphosis, that it is surprising to find an equal rigidity in the days of alternation of generations. Without citing an extensive and familiar literature, attention may be called to the various claims that have been made as to the morphological nature of the endosperm of angiosperms. Ever since the comparative morphology of the vascular groups was uncovered by HOFMEISTER, belief has been general that the endosperm of angiosperms is gametophytic tissue which develops after fertilization. It was easy, even in the days of HOFMEISTER, and much more so now, to obtain from gymnosperms what seems to be abundant confirmation of this claim. Throughout that group there is a distinct tendency to differentiate eggs earlier and earlier Botanical Gazette, vol. 51] [380

An American Lepidostrobus

The remarkable uncovering of the structure of paleozoic strobili and seeds during the last decade, chiefly from sections of English and French material, has brought to the American morphologist a feeling of disappointment that the extensive American Coalmeasure deposits have yielded these structures only as impressions or casts. Extended inquiry has failed to discover such petrified material in any of the collections, so that its occurrence is evidently quite unusual. A short time since there came into our hands, through the courtesy of Dr. STUART WELLER, of the Department of Geology of this university, a specimen of Lepidostrobus, the strobilus of Lepidodendron, that was evidently petrified. It had been collected in i900, in a coal pocket in Warren County, Iowa; and in January I9II came into the possession of Professor JOHN L. TILTON, of Simpson College, Indianola, Iowa, who brought it to this university, and in whose collection a portion of the sectioned cone is to be found. The specimen is not a complete strobilus, but a fragment from near the upper end, broken at an angle above, and squarely across below. As a consequence, if the strobilus was heterosporous, all evidence of the megasporangia had disappeared with the missing lower portion. The fragment is 6 cm. long and 5 cm. in diameter at base, and all the structures proved to be very well preserved except the axis (figs. i and 2), which had been almost completely destroyed and replaced by calcite and pyrites. The strobilus was a mature one, which had fallen and remained in the water or moist soil, fQr rootlets had penetrated between the sporophylls here and there, and the rootlets in turn had been attacked by a fungus. Nearly all of the sporangia are empty, only a few spores being occasionally in place, but masses of spores occur in many places between the sporophylls.

Contribution to the Life History of Lilium philadelphicum

A group of research students, in connection with a general study of monocotyledons, selected Lilium PFiladelplkicumn as a suitable type for somewhat special study. The end in view was to examine those structures so fully described by Guignard for L. Martagon, and treated in a supplementary way by subsequent investigators of the same plant. Abundant material of the local L. P/iiladelp/zicum was obtained, and the cultivated L. tigrinum waz used also for comparison. The numerous preparations of thirteen investigators gave unusual opportunity for a broad range of observation, so that the facts herein set forth may be regarded as fairly established. As to questions of interpretation, there may well be diversity of opinion, as the present necessities of the case make almost every step in interpretation an inference. It is evident that the association of phenomena will suggest a causal relation, whose reality is plainly only an inference. Moreover, the comparatively obscure structures concerned in cell activity are peculiarly open to misinterpretation, both as to origin and function. The subject, therefore, is one in which dogmatism is singularly inappropriate, and in which every proposed causal sequence of events must be regarded as a suggestion rather than as an established fact. Inasmuch as this work upon Lilium was but supplementary to the more formal investigation in which each investigator is engaged, my original purpose was to organize under a single caption all of the results that seemed worthy. As the work developed, however, certain parts of it seemed to demand more

The Embryogeny of Zamia

(WITH PLATES VI-VIII) OUR knowledge of the development of the embryo of Cycadales is very meager, being largely included in Treubs (5) account of Circas circinalis and Ikenos (8) of Cycas revoluta. These two accounts agree in every important particular, and deal chiefly with the development of the proembryo. The following facts were established: the egg nucleus divides, and successive simultaneous divisions give rise to a large number of free nuclei; the cytoplasm of the central region of the egg becomes vacuolate and then completely disorganizes; the remaining cytoplasm becomes parietal, massing somewhat toward the bottom of the egg; in this parietal layer the numerous free nuclei are imbedded, being equidistant from one another and forming usually a single layer except at the base of the egg, where simultaneous nuclear division begins again; later, walls appear, and the proembryo becomes a sac somewhat thickened at base, but with the wall composed of one or at most two layers of cells. This history differed so much from that of Ginkgoales and of Coniferales as known at that time that it seemed to stand somewhat stiffly apart among gymnosperms. A series of collections of Zamia floridana was obtained from southern Florida during the spring and summer of 1902. Some collections consisted only of the ovulate strobili, but in most cases the entire plant was secured. As stated by Webber (II), the ovulate strobili continue in their development for some time after removal from the plant, and we have observed mitotic figures in ovules after the strobilus had been lying in the laboratory for nearly two weeks. Entire plants sent from Florida in June and July were potted, and they continued to develop

A Homosporous American Lepidostrobus

Strobili of Lepidodendron so perfectly preserved that they can be sectioned and their minutest structures studied are common in European coalfields. Many of these strobili show heterospory, the megasporangia being at the base of the strobilus, the microsporangia above. The extensive literature of the subject is fully cited by SCOTT, and SEWARD,2 and need not be repeated here. The extensive American coalfields, with but two exceptions, have yielded nothing but casts as yet. Perhaps the reason for this seeming scarcity of petrified material is that it has not been looked for carefully by competent observers. In i9ii there came to this laboratory from Professor JOHN L. TILTON, of Simpson College, Indianola, Iowa, a well preserved fragment of a strobilus from the coalfields of Warren County, Iowa. This fragment, from above the middle of the strobilus, showed small spores, but of course nothing concerning heterospory could be determined. This specimen, the first American Lepidostrobus to be sectioned, was fully described by COULTER and

The Origin of Gymnosperms and the Seed Habit

1. A great Cordaites plexus, more extensive than the one usually included under that name, represented the characteristic Palaeozoic seed plants. 2. It was probably derived from homosporous-eusporangiate Filicales, represented today most abundantly by the Marattia forms and their allies, and was the most common Palaeozoic type of Filicales. 3. From it the gymnosperm lines, at least the cycads and conifers, were derived, the usually recognized Cordaites representing a transition stage towards conifers. 4. The frequent independent appearance of heterospory is to be expected, as it probably results from inequalities of nutrition in connection with the development of antheridia and archegonia. 5. The retention of the megaspore, resulting in the seed habit, follows the extreme sterilization of the megasporangium, which is attained with the organization of but one megaspore. With the development of a single megaspore imbedded in sterile tissue, shedding becomes mechanically difficult, unnecessary, and even disadvantageous from the standpoint of nutrition. 6. The retention of the megaspore was followed by the development possibly of seed coats, through the well-known effect of fertilization upon adjacent tissues; by immediate germination of the oospore, on account of the favorable conditions and the abundant supply of available nutrition; and by the checking of the developing embryo by the mature seed structures, resulting in the characteristic intra-seminal and extraseminal stages of germination. 7. The first retained megaspores were doubtless directly exposed to the microspores, and in Cordaites and cycads a pollen chamber of varying depth and extent is associated with the early stages of siphonogamy, with which spermatozoid habit was more or less associated. 8. The pollination of gymnosperms is but a continuation of the ordinary method of dispersing aerial spores employed by cryptogams, the chief result of the retention of the megaspore upon the male gametophyte being the development of siphonogamy.

A text-book of botany.

The study of plants may be approached from so many points of view that every laboratory has developed its own method of undergraduate instruction.

New or Noteworthy Compositæ from Guatemala

Mr. John Donnell Smith has placed in my hands for determination his recent and large collections of Compositae from Guatemala. From the long and interesting list of species that these collections contain, the following have been selected for publication as being new or especially noteworthy. In the final and critical study of species the herbarium and library of Harvard University were used, and thanks are due to Dr. Sereno Watson for his courtesy in supplying every facility for such study. Mr. Henry E. Seaton, my assistant, made all the dissections and rendered valuable service in generic deter-

On the Appearance of the Relation of Ovary and Perianth in the Development of Dicotyledons

tively long time. Cultures were made of Asplenium and Onoclea Str-uthiopteris in 1884, from spores sown August 31. They grew rapidly and soon developed quantities of antheridia, but in the case of Asplenium, no archegonia. As cold weather came on, although the prothallia were kept in the houLse, growth ceased almost entirely, but was resumed in the spring, the prothallia appearing perfectly healthy. Large numbers then developed archegonia, and subsequently young plants, but some of them are still (August 14) perfectly vigorous, and growing. The older male prothallia assume very irregular forms, reminding one somewhat of the prothallia of Equiseta, but the fenmale retain nearly the same form as they have when young although they may be slightly irregular. The sexual organs continiue to form as the prothallia grow, so that in the older ones the number is very large. A female prothallium of Asplenium, about onie cm. in diameter, examine(d August 12, had over one hundred anid twenty-five archegonia, buit no antheridia. One of the archegonia had been recently fertilized, but the remainder were abortive. It sometimes happens that several archegoniia will be impregnated, but only onie embryo apparently ever develops perfectly. In the older prothallia of Onoclea Str-thiopter is, especially early in the spring, large quantities of starch were observed.