SCIENCE- GOSSIP. 



319 



STRUCTURAL and PHYSIOLOGICAL BOTANY. 



CONDUCTED BY HAROLD A. HAIG. 



Karyokinesis in Helleborus Ovules. — The 

 stages in cell-division by mitosis are well brought 

 out in the nucellar tissue of the young ovules of 

 HellehoruH niger (Christmas rose), especially at the 

 base of the embryo-sac. All phases may be made 

 out, from the iirst gathering together of the masses 

 of chromatin to form an axial mass of intertwined 

 fibrils (monaster stage) to the iigure where the 

 loops are seen on either side of the plane, where 

 the cell-plate will ultimately form, and that in 

 which the two separate sets of loops form well- 

 defined masses joined by the intermediate spindle 

 of achromatin fibrils (diaster stage). The stain 

 used, which gives the best result, is a triple stain of 

 haematoxylin, safranin, and toluidin-blue. 



Wall-markings in Epidermal Cells. — The 

 epidermis of HyaolntJms (fig. 1) offers an interesting 

 study in connection with the markings sometimes 



Fig. 1. Transverse striatum on the outer w.ill of epidermal 

 cells of Hyacinthus. 



seen on walls of certain parenchymatous cells. 

 Each somewhat elongated cell is seen to possess a 

 wall, upon which the most delicate transverse or 

 scalariform thickenings are arranged at right 

 angles to the long axis. They are probably of 

 protective value, and serve to keep the thin outer 

 walls in position when the protoplasmic layer 

 becomes so thin as to form very little elastic 

 support. In the same cells may be seen, on stain- 

 ing with suitable reagents, the peculiar elongated 

 nuclei characteristic of quickly growing cells. 



Recent Research. — M. T. Meehan finds that 

 vegetable parasites, such as fungi, can by their 

 presence in certain |3lants cause the latter to pass 

 from the hermaphrodite into the unisexual form 

 (" Cosmos," Feb. 1902). Whether this is because 

 a certain amount of material is used up in the 

 nutrition of the fungus, thus removing sub- 

 stance which would otherwise have been useful to 

 the plant ; or whether there is some direct in- 

 fluence exerted by the parasite, is not certain. 

 The phenomenon, however, would appear to be 

 explained in a satisfactory manner on the nutri- 

 tion hypothesis. Analogues of this conversion are 

 present in the lower plants, where, as in certain 

 thallophytes and fungi, spore-formation takes the 

 place of the usual sexual process (Vmicheria). 

 MM. E. Charabot and A. H6bert, in investi- 

 gating the action of sodium chloride upon plants, 

 have determined (1) that there is a percentage 

 increase in the organic substances of the whole 

 plant ; (2) a relative diminution in the total 

 quantity of water present. The paragraph in ques- 

 tion does not give the actual quantities of salt 

 used in the experiments. M. Noel Bernard (" La 

 Nature," February 1902) has recently discovered a 

 most important biological point with regard to 

 the potato-tuber. He finds that the tuber is not, 

 as was formerly supposed, a true product of 

 vegetable growth, but the result of a pathological 

 process brought about by the presence in the 

 cortical cells of the aerial roots of certain fungi 



belonging to the group Fusarium. The mycelium 

 of these penetrates the cell-walls at an early stage, 

 and modifies the action of the contained proto- 

 plasts. The article in question emphasises the 

 fact, which has long been known, that potato- 

 plants may be reared from seed, but that no tubers 

 are formed on the aerial roots of such plants. The 

 fungus is thus absent from the seeds, and only gets 

 into the cortical tissues of the roots when these are 

 led underground. In a substratum into which no 

 fungi are allowed to enter, no tubers are subse- 

 quently formed. The whole discovery is an in- 

 teresting addition to the biology of symbiosis. 



A New- Botanical Journal. — In the "New 

 Phytologist " we have a publication which, although 

 small in dimensions, contains the results of in- 

 vestigations of a high degree of excellence. 'Mr. 

 Tansley, the editor, states that . it is his intention 

 to keep the journal fairly technical, but also to 

 introduce material that will be quite readable to 

 students of botany, who take a general interest in 

 biological science. An interesting feature in the 

 first two numbers is an article on the " Revision 

 of the Classification of the Green Algae," by F. 

 Blackman and A. G. Tansley, which will probably 

 be continued into several numbers. We cannot, of 

 course, attempt to give any definite criticism as 

 yet, but it appears that for students who sxoecialise 

 in any department of botany this journal will 

 prove of very great value. It is excellently printed, 

 and is of a convenient size. 



Definitive Nucleus and Egg - cell in 

 Caltha.; — In the February number of SciENCE- 

 GossiP I called attention to some of the results 

 that may be obtained in photomicrography by 



Fig. 2. Embryo-sac of CaJtha showing definitive nucleus, the 

 synergidae and the egg-cell. 



careful and suitable staining. I regret that the 

 specimens . shown in connection with that para- 

 graph did not reproduce so well as might have 

 been wished, but I append a photomicrograph, 

 taken under ^■^' oil immersion, of a stage in the 

 embryo-sac of Caltlia falustris (fig. 2) where the 

 definitive nucleus, the synergidae, and the egg-cell 

 are well seen. 



[A transposition is needed in explanatory texts 

 of figs. 3 and 4, ante, p. 272.— Ed. " Struct. Bot."] 



