SCIENCE- GOSSIP. 



laticiferous cell, which stains deeply with toluidin 

 blue. The wall of our isolated element also stains 

 well with that substance. Another point to be 

 noted is the presence of very fine nuclei in the 

 cells of the spongy parenchyma of a size which one 

 rarely sees in other plant-cells. 



A Conjugating Yeast. — Under certain con- 

 ditions of existence Saccharomyces seems to 

 possess the power of "rejuvenescence" by means 

 of the process of conjugation. In a paper by Mr. 

 B. T. P. Barker, B. A., in " Proc. Roy. Soc.,""july 

 1901, the various experiments on this subject are 

 explained at some length. The essential points 

 are that vigorously growing cells were observed in 

 a drop of distilled water ; the contents of a pair 

 of cells first of all became vacuolated, and a beak- 

 like process was put out by each cell. These j)ro- 

 cesses met and fused, and the protoplasmic contents 

 communicated through the passage thus formed. 

 After a few hours the protoplasm began to contract 

 and small round masses formed, which subse- 

 quently developed into spores. 



OosPHERES OF PiNUS. — On examining a longi- 

 tudinal section taken through the embryo-sac 

 of some gymnosperms (Pinvs nylredris and P. 

 A nk 



Fra 3. Sections of Austrian PI^'E-ovuLl•:s. 



Vratrn hii Harold A. Haia, from Photo-micrograph hii 

 A. E. Powell 



A. LoNaiTunix.\L section through three Aechegoxi.4, 



SHOWING OOSPHERFS ; IN THE MIDDLE ONE, DIVISION 

 HAS COMMffNCED. 



ni. Apex of embryo-sac. a. Archegonium. o. Oosphtre, showing 

 central nucleus and numerous vacuoles, c, Oanal. 



B. High-power dbawing of "receptive spot." 



o. Oospliere. h. Vacuoles, c. Canal, r. Portion of separated 

 protoplasm forming the receptive spot. 



anstraea), one cannot fail to notice the relatively 

 large size of the archegonia and their contained 

 corpuscula or oospheres. The protoplasm of these 

 latter is very granular, and there are usually a 



large number of good-sized vacuoles scattered 

 throughout its substance. The nucleus is, so to 

 speak, immense, and is very clear, with a small 

 nucleolus near the centre (see fig. 3). An import- 

 ant point to be observed about the time when 

 fertilisation commences is the existence at the- 

 micropylar extremity of the oosphere of a mass of 

 protoplasm somewhat clearer than the rest, and 

 apparentlj' cut ofl: from the top of the oosphere. 

 It constitutes the "receptive spot" for the male 

 generative nucleus, and is probably to be looked 

 upon as being homologous with the "polar bodies" 

 that are thrown off by the animal egg-cells just at 

 the end of maturation. It may, however, be pos- 

 sible that this mass of protoplasm is the remains 

 of the "ventral canal cell" formed during an 

 early stage. 



Development op Tulipa gesneriana. — 

 D. Ernst has worked out some interesting points- 

 with regard to the changes occurring during and 

 after fertilisation in the case of Tulipa gesneriana 

 (" Flora," Ixxxviii. pp. 37-77), and has shown also 

 the existence of polyembryony in this plant. He 

 found that of the male nuclei in the pollen-tube 

 one fuses with the egg-cell nucleus, whilst the 

 other fuses with one of the polar nuclei ; so that 

 ultimately the definitive nucleus is the result of 

 the fusion of three nuclei. That is to say, the two 

 polar nuclei, and one of the male nuclei, from the 

 pollen-tube. This may be considered as a form of 

 double fertilisation. 



Recent Work on Laticiferous Tubes. — For 

 some time it was thought that the latex in the 

 system of tubes of some plants (^Euphorbia, Ison- 

 andra, etc.) was actually modified protoplasm, but 

 recently a work written on this subject by Hans 

 Molisch has more or less disproved this. According 

 to this observer, there is a cytoplasmic layer close 

 to the wall of the tube, and inside this a space 

 filled by the latex. The nuclei have also a peculiar- 

 feature, in that there is a clear zone just inside 

 the. nuclear membrane; but this maybe only the 

 result of the action of certain reagents. There is 

 also some account of mucilage tubes occurring in 

 various plants, and investigation of the several 

 substances present in the latex and mucilage — 

 soluble and insoluble proteicls, carbohydrates, and 

 oils — are found, and in some cases it was discovered 

 that the leucoplasts produced, not starch-granules, 

 but oil-globules. 



Leaf Comparisons. — The "interesting minor 

 point " mentioned at p. 95 ante is, in fact, anything 

 but minor. It is a matter of very eminent import- 

 ance indeed, and is alluded to in that veritable 

 mine of botanical lore, the " Histoire Physiol, des 

 Plantes d'Europe," published by Vaucher so far 

 back as the year 1841. He says: "The leaves of 

 Picea abies are true leaves, whose petioles, like 

 those of juniper, are laid down upon the cortex 

 which has given birth to them, and are detached 

 sooner or later in the form of epidermis ; but the- 

 leaf properly so called or its blade is similarly 

 formed in pines, firs, and piceas. The leaves of 

 Pini/s are true branches which spring from the 

 interior of the wood, and perhaps even of the pith,. 

 and the woody connection of which can be easily 

 remarked." Descanting on the leaf of pine, he 

 says : " The sheathed leaves must be regarded as 

 belonging to so many branches regularly aborted."" 

 These sheathed leaves are produced in the axils 

 of first-formed simple leaves, which disappear^ 



