I go 



SCIENCE-GOSSIF. 



those of the nucellus and seed-coat, and there is 

 thus every facility for rapid diffusion of food 

 material during the process of reproduction. 

 Various views are held concerning the manner in 

 which the altered relative position of xyleni and 

 phloem is brought about, but these need not be 

 here discussed. 



Adaptability of Plants. — Prince Kropotkin, 

 writing in the " Nineteenth Century " (September, 

 pp. 423-431), reviews the work that has recently 

 been done in establishing the fact that variability in 

 plants is very largely determined by the surround- 

 ing conditions of moisture, warmth, light, etc. He 

 points out that Alpine plants taken awa}' from 

 high altitudes and grown in a valley lose many of 

 their Alpine characteristics, and vice versa ; there 

 is also a brief account of the work of the great 

 botanist, De Vries, in this direction, with especial 

 mention of the variations he produced in the poppy ; 

 for instance, the production of the many-headed 

 variety by alterations of manure and other nutrition 

 factors — a j^rocess De Vries called " nutrition- 

 variation," for it depended chiefly upon the nature 

 and quantity of the food-material supplied. There 

 are other interesting notices concerning the varia- 

 bility of plants under changing conditions, and 

 stress is laid upon the fact that in some plants 

 (^Oenothera lamarcldana) accidental variations have 

 arisen that possessed the power of reproducing 

 their kind exactly even for more than four or five 

 generations. 



The Structure of the Nucleolus. — The 

 " definitive " nucleus of Caltlia paludris offers 

 many interesting points for observation. In tlie 

 first place, its large size, relatively to the dimen- 

 sions of the embryo-sac, renders great aid to investi- 

 gation, as also does the comparative ease with which 



Fig. 2. Longitudinal Skction through E>u3ryo-sac of 

 Caltha palustkis. 



(Dratc/i under -^^ oil-inunersion.) 



t. Tapetal -layer, a. Antipodal cells, p. Mass of protoplasm. 

 «. N I- cleasol embryo-sac. n'. Nucleolus, f. Egg-cell (?). 



sections may be made of the sac in the ovules. 

 A longitudinal section of an ovule of Caltha at a 

 certain stage priortofertilisation will, if the section 



be successful and carefully stained with haemat- 

 oxylin, safranin, and toluidin blue, show us all 

 the structures contained in the embryo-sac. These 

 are (a) the "definitive nucleus," (*) the "syner- 

 gidae " and egg-cell at the micropylar end of the 

 sac, and(c) the " antipodal cells," three in number, 

 at the opposite end. (See fig. 2.) In the defini- 

 tive nucleus we easily make out the nuclear 

 membrane, the chromatin masses, and the large 

 nucleolus. This latter has a well-defined border, 

 and moreover this border is seen to be of fair 

 thickness, and may at certain points be depressed 

 towards the interior, which is clearer. Obviously 

 in this case the nucleolus has the structure of a 

 vesicle, and it is probable that all nucleoli are of 

 this nature, being filled with a clear fluid of an 

 oily consistency. 



Partial Suppression of Phloem in Wild 

 Balsam. — It may interest botanical readers to in- 

 vestigate or discuss the reason why the ring of 

 phloem is to a great extent suppressed in the stem 

 of the wild balsam {Impatiens). There are certain 

 points of a transverse section where the large 



Fig. 3. Traxsverse Section through Stem qv Impatiens 

 noli-me-tangere. 



e. Epidermis, p. Phloem. xy. Xyleni. .v. Part of inter- 

 fascicular xylem outside which no phloem has beea developed. 

 p. XII. Proto-xylem of primary bundle. 



obviously primary bundles may he seen, the 

 phloem being outermost ; but between these there 

 is only a fully-formed ring of xylem, with a few 

 cambial cells lying just outside it. Tlie protoxylem 

 is to be seen in the primary bundles, and radiating 

 from each of the annular vessels of this primary 

 xylem are cells of a peculiar shape, giving a sort of 

 stellate appearance to the whole. 



A Modified Form of Chalazogamy. — Dr. 

 Longo employs the term " mesogamy " in cases 

 where, as in certain of the Amentiferae, the pollen- 

 tube traverses the tissues of the funiculus and the 

 outer integument of the nucellus before entering 

 tlie micropyle (liendieonti clella Jl. acacl. del lineei). 

 With regard to the direction taken by pollen-tubes 

 in their passage towards the embryo-sac, it has 

 been noticed that in Gymnosperms it is by no 

 means unusual to find that the tube, instead of 

 passing to the upper end of any one of the canals 

 of the archegonia, pierces the nucellar tissue, and 

 so reaches the apex of the embryo-sac. 



