314 PROCEEDINGS OF SOCIETIES. 



larians. Tliese structures, however, seem to exhibit no satisfactory 

 evidence of behig so. In the first i^lace, these organisms are now 

 calcareous instead of sihcious. It has been suggested that their 

 sihcious elements were removed and replaced by carbonate of lime, 

 but this appears to be most improbable. Prof. Eoscoe and Prof. 

 Schorlemmer agree in stating that they would require over- 

 whelming evidence before they would be prepared to accept such 

 an explanation of the present condition of these objects, or of the 

 fact of the substitution of carbonate of lime for silica, that such an 

 explanation renders necessary. Count Castracane has published 

 an account of a process by which he reduced numerous specimens 

 of coals to very minute quantities of coal-ash, and has stated that he 

 found in tliese ashes numerous marine and freshwater DiatomacecB. 

 Prof. Eoscoe kindly allowed one of the ablest assistants in his 

 laboratory at Owen's College to pre^^are analyses of a number of 

 coals according to Count Castracane's method. The residual ashes 

 of these preparations have been examined microscopically by Prof. 

 Williamson, and in no one of them can a trace of a diatom be 

 found. Beyond stating the fact, he is wholly unable to account for 

 the discrejDancy between his results and those of the Italian 

 observer. • So far as his present observations go, he finds himself 

 compelled to conclude that we have no proof of the existence of 

 radiolarians or of DiatomacccE in the British carboniferous rocks. — 

 " On the Association of an Inconspicuous Corolla with Protero- 

 gynous Dichogamy in Insect-fertilized Flowers," by Alex. S. Wilson, 

 M.A., B.Sc. The majority of conspicuously-coloured flowers whose 

 cross-fertilization depends on their being easily seen by insects, are 

 proterandrous. Such plants have their flowers placed in close 

 inflorescences, as, for example, in Erica, Calhina, Vacci)iium , Digitalis, 

 Linaria, Gladiolus, &c., and occasionally the flowers are secund, or 

 placed on one side of the axis, thus becoming more conspicuous. 

 In the indefinite mode of inflorescence the older flowers are placed 

 at the lower part of the flowering axis ; hence in the commonest 

 form of inflorescence with proterandrous flowers, the lower flowers 

 are in the second or female stage at the time when those in the 

 upper part are in the first or male stage. In proterogynous 

 dichogamy with indefinite inflorescence, the older flowers are in the 

 second or male stage when the upper and younger flowers are in 

 the female stage. In Scrophularia nodosa we have a plant in which 

 proterogynous dichogamy is associated with an inconspicuous corolla. 

 The stigma after fertilization is removed out of the pathway to the 

 nectar by the bending back of the style on the outside of the corolla, 

 while the stamens straighten out to occupy the place formerly held 

 by the stigma. The corolla is small and obscurely coloured, being 

 greenish, tipped with brown. The inflorescence is lax, and the 

 flowers scattered all round the axis. The odour of the flowers 

 and the presence of a nectariferous gland shows that the plant is 

 fertilized by insects, and not by the wind. Among such incon- 

 spicuously-coloured flowers, proterogynous dichogamy seems to 

 prevail, just as proterandiy is characteristic of brightly- coloured 

 flowers. Hitherto it has not been shown how an entomophilous 



