272 



SCIENCE- GOSSIP. 



demonstration of such structures as the sieve- 

 plates of sieve-tubes, but it is doubtful if the red 

 light that comes through is very powerful actini- 

 cally ; and in cases such as these it would perhaps 

 be more satisfactory to rely upon drawings taken 



Fig. 2. t The embryo-sac of Caltha palustris, showing nucleus 

 of embryo-sac, antipodals, and faint outline of etrg-cell. 



from actual observation than upon the photomicro- 

 graph. In the photography of most transverse 

 sections of stems, roots, and many other botanical 

 specimens we may use with advantage as our 

 staining material either toluidin-blue, haema- 



Fig. 3. Portion of trans, section lupulus, showing ring of 

 cambium and young wood and phloem. 



toxylin. or both, for tissues stained with them turn 

 a beautifully actinic blue on treatment with tap- 

 water (not distilled water, because it requires the 

 minute degree of alkalinity thattap-waterpossesses). 

 We have obtained very satisfactory results with this 



- 



Fir;. 4. Longitudinal section through bud of one of Abietineae 

 (Pin us). 



method. With regard to differential staining a com- 

 bination of methyl-green and toluidin-blue, or 

 separate staining with these two, would give good 

 results, as the actinic power of the former is much 

 less than that of the latter. Tissues stained with 



eosin or carmine will, of course, give a result ; but 

 it is difficult to obtain good definition, and the cell- 

 walls, etc., only come out faintly, with somewhat 

 blurred outlines. But a differential stain with 

 eosin and toluidin-blue is quite satisfactory. The 

 structures should be mounted so as to exclude all 

 air-bubbles ; a photomicrograph of delicate tissues 

 in which a large bubble is incorporated is, as a 

 rule, quite spoilt on account of the effects of 

 reflection and refraction at the surfaces of the 

 bubble. Styrax is a good mounting medium. Canada 

 balsam being rather yellow even in thin films. I 

 have to express my thanks to Mr. A. E. Powell for 

 the photomicrographs (see figs. 1. 2, 3, 4), which 

 were taken from specimens in nry possession. 



Transfusion Tissue. — In the central cylinder 

 of the acicular leaf of many gymnosperms (stone 

 pine) we find just internal to the endodermis a 

 peculiar form of tissue the component cells of 

 which have small bordered pits in their walls; 

 these pits have the same structure as those met 

 with in the tracheides of the stem or root xylem. 

 In a good section one can make out that the 

 phloem portion of the two fibro-vascular bundles 

 of the leaf is in intimate connection with this 

 transfusion tissue, in fact the two gradually merge 

 into each other. This is a very important point 

 with regard to the translocation of proteid and 

 carbohydrate elaborated food-material, from the 

 cells of the mesophyll into the phloem, and so to 

 the stem and other parts of the plant. The 

 presence of bordered pits renders the passage of 

 aqueous solutions easy, but whether both colloids 

 and salts pass, or only one, is a point difficult to 

 decide ; in the tracheides of the stem it is probable 

 that only dilute salt solutions pass. 



Recent Research. — L. Guignard, in the " Jour. 

 de Bot.," 1-9, 1901, has recently determined double 

 fertilisation for Thmas major. One of the syner- 

 gidae disintegrates soon after the entrance of the 

 pollen tube ; the other remains intact until after 

 several divisions have occurred in the embryo. 

 The oospore has no quiescent stage, but divides 

 immediately after fusion. In all previous cases of 

 double impregnation the definitive nucleus divides 

 before it is fertilised, but here, many times, two 

 embryos were seen lying side by side, with the 

 definitive nucleus lying between them still un- 

 fertilised. The upper antipodal cell enlarges 

 during a long period after fertilisation ha.-' 

 occurred. B. E. Livingston, in " Bot. Gaz.."' 30, 

 289-317, 1901. investigates 

 stimulus causing changes 

 morphic green algae ; he 

 on the change of form of varying concentrations 

 of Knop's Solution, a nutrient solution containing 

 several salts, to be due to changes in the water 

 contents of the cell. The " Journal of Applied 

 Microscopy " lays stress upon the fact that we 

 have in this consideration of the effects of osmotic- 

 pressure changes upon the form of cells, an 

 entirely new field of physiological investigation. 

 Observations on the Embryogeny of Xelumbo, a 

 formerly supposed dicotyledon of somewhat hypo- 

 thetical series, by H. L. Lyon, have determined 

 the true monocotyl nature of the embryo, thus 

 placing it in a sub-series co-ordinate with the Pota- 

 mogetonaeeae, Alismaceae, and Butomaceae in the 

 series Helobiae. " Minnesota Bot. Studies." This 

 is important both from the embryological and 

 classification point of view. 



the nature of the 

 of form in poly- 

 believes the effect 



