HABDWICKE'S SCIENCE-GOSSIP. 



187 



trefoils, which are so greedily devoured by cattle, < 

 afford an important supply of the calcareous or 

 other salts which are essential in the animal eco- 

 nomy. Has any agricultural chemist ever estimated 

 the quantity, by weight, of the short prismatic 

 crystals in a truss of clover ? They present in the 

 clovers and other trefoils lovely microscopic objects, 

 suggestive, too, of utility. Nor are such observa- 

 tions alone in proving the high value of the micro- 

 scope in explaining or directing practical operations 

 in the cultivation of useful plants. 



Floral Estivations.— At the meeting of the 

 Linnean Society, held on June 1st, the -Rev. G. 

 Henslow read a paper on floral aestivations, in 

 which, after giving the eight kinds, viz., distichous, 

 tristichous, pentastichous, half-imbricate, imbricate 

 proper, convolute, valvate, and open, he explained 

 their origin, and specially dwelt upon the new 

 term " half-imbricate," which he applied to a very 

 large number of cases ranging from perfect regu- 

 larity to extremely irregular and zygomorphic flowers 

 of the pea and snap-dragon. The author then 

 showed how that, as well as the fifth and sixth 

 kinds were successively deducible from the third or 

 psntastichous (quincuncial) by merely shifting one 

 edge of the second part under the adjacent edge of 

 •the fourth part. The author added a note on a new 

 theory of the cruciferous flower, based on a quinary 

 type, and which, by symmetrical reduction (i. e. the 

 fifth part of each whorl would be suppressed) the 

 remaiuing fours would, by further arrest, due to 

 adaptations to insect agency, form the normal 

 flower. He also disputed the teuability of Chorisis 

 in the pairs of long stamens, regarding their occa- 

 sional union as indicative of evolutionary advance 

 and not retrogression ; as cohesion is a subsequent 

 stage to freedom, except in the rare cases of atavism 

 indicated by solution and dialysis. The author 

 ■called in question the justness of Pfeffer's view of 

 the corolla of Primula, being an outgrowth of the 

 andracium, by showing (a) the position of the 

 stamens to be explained by the staminodia of Samo- 

 fas, (b) that the corolla appearing subsequent to 

 the stamens is no anomaly, (c) that the fibro- 

 vascular bundles are ten in number, of which five 

 are intermediate, and (d) that phyllotactical {estiva- 

 tion were those of true leaves ; so that all these 

 facts conspired to render the theory unteuable. 



GEOLOGY. 



Fossil Carboniferous Plants. — Professor 

 W. C. Williamson, of Owen's College, Manchester, 

 has just contributed the eighth of his valuable 

 memoirs on the above subject to the Royal Society. 

 After describing in it a peculiar stem of a new 

 species of fern, he proceeded fully to notice the 

 stems and seeds of Gynmosperms. Of the former, 



various modifications of the Sterubergian Dadoxy- 

 lons are described, and shown to correspond very 

 nearly to many recent conifers, though with distinc- 

 tive features of their own, especially in the struc- 

 ture of their woody fibres, and in the leaf-bundles 

 of some species being given off in pairs. The 

 author still excludes the Sigillariae from the Gym- 

 nospermous group. The most important novelties 

 are the Gymnospermons seeds, exhibiting their in- 

 ternal organization, found in France by M. Grand- 

 Eury, and by the author in this country. Of these 

 he describes a number of new genera aud species 

 in addition to the Trigonocarpons previously 

 described by Mr. Binney and Dr. Hooker. The 

 most remarkable of these is one designated Lageno- 

 stoma ovoides, in which a large flask-shaped cavity, 

 inclosed within a crenulated canopy, occupies the 

 apical end of the seed, between the apex of the 

 endosperm and the exostome. Brongniart believed, 

 with reason, that such cavities have originated in 

 the absorption of the apex of the nucleus, leaving 

 the corresponding part of the nucular membrane to 

 form the cavity or " lagenostome." In this lageno- 

 stome large pollen-grains are found in many cases. 

 Brongniart designates it the " cavite pollenique." 

 Examples of several other seeds presenting generic 

 and specific modifications of the same type, as well 

 as several species of the well-known genus Cardio- 

 carpum and of Trigonocarpum. In all these the 

 primary nucleus seems to have been absorbed, being 

 now only represented by the investing nucular mem- 

 brane. Within this is an inner structureless bag, 

 which, in some of the Cardiocarpa, is filled with 

 parenchyma, and which appears to represent the 

 secondary perispermic membrane, or what is really 

 the endospermic membrane, or primary embryo-sac 

 of the Gymnosperms. The intimate structure of 

 Trigonocarpum agrees with Dr. Hooker's descrip- 

 tion of it so far as the longitudinal sections are 

 concerned, save that here also a "cavite pollenique" 

 exists. Transverse sectious show that the well- 

 known sandstone casts of Trigonocarpum do not 

 represent the external form of these fruits, but are 

 casts of the interior of the hard endotesta. This 

 latter was not trigonous externally, like the common 

 specimens, but had twelve longitudinal ridges, three 

 of which, corresponding with those of the sand- 

 stone casts, were more prominent than the rest. 

 The endotesta was iu vested by a delicate paren- 

 chymatous sarcotesta. All these seeds appear to 

 have cycadean rather than coniferous affinities. 

 One winged seed alone (Polypterospermum), from 

 the uppermost coal-measures at Ardwick, resembles 

 a true conifer. In conclusion, the author calls atten- 

 tion to the number of yet unknown stems and 

 leaves of Phanerogams, which must have belonged 

 to the numerous seeds now known to exist in the 

 coal-measures of England, France, and North 

 America. 



