ZOOLOGY AND BOTA^JY, MICROSCOPY, ETC. 777 



especially Urtica dioica, Bohinia pseudacacia, Quercus sessiliflora, and 

 Phaseolus multiflorus, and finds the development of this tissue greatly 

 dependent on external conditions. These conditions determine the 

 ])rop()ition in which the various tissues or kinds of cells are developed 

 from the initial cambium-cells ; but the extent of this variability is 

 limited for each species. The formation of the libriform fibres, or of 

 the fibre-cells which replace them, appears to be in all cases a 

 mechanical one. 



Secondary Medullary Rays.* — Herr E. Schmidt has investigated 

 the mode of formation of the secondary medullary rays, esj)ecially in 

 Pinus sylvestris. They originate in the cambium, but not from any 

 sudden change ; rather as the final result of a series of changes 

 gradually leading up to them. 



Foliar Medullary Bundles of Ficus.j— Conte Dr. L. Macartili finds 

 no trace of medullary bundles in the stem of any species of Ficus ex- 

 amined ; on the other hand, they are numerous in the leaf-stalk and 

 veins of the leaf. They always originate from the node, and arc 

 portions of leptome which separate, for a longer or shorter distance, 

 from the leptome of the normal bundles, towards which they then turn, 

 to be reunited with them. 



C4") Structure cf Organs. 



Ovuliferous Scales of Conifer8e.| — Prof. F. Delpino discusses the 

 morphological value of the ovuliferous scales of the Abietinege and other 

 Coniferae. He states that in the Pteridophyta, Gymnosperms, and 

 Angiosperms the evolution of the carpid or fertile leaf is manifestly 

 homologous, with slight diflerences. The carpid or fertile leaf must be 

 regarded as a phyllome ideally divisible into three, and frequently 

 actually tripartite, w^ith the median division sterile, and the two lateral 

 divisions fertile and ovuliferous or sijorangiferous. If the j^hyllome 

 remains entire we have the pleurosporangium of many ferns, or pleuro- 

 spermy, which is normal in the Cycadeae and in nearly all Angiosperms. 

 But frequently in the fertile leaf the sjiorangifcrous divisions separate 

 from the median sterile plane of division into a bundle opposed and 

 superposed to the median division, as occurs in Aneimia. It may then 

 happen that, from the first, all the fertile divisions coalesce into a single 

 fertile body opposed and superposed to the sterile division ; and to this 

 phenomenon the author aj)plies the term antii^iwrangism in Pteridophyta, 

 antispermy in Phanerogams. 



Antisporangism occurs in at least two sections of the Pteridophyta, 

 and independently of one another — in the Marattiacese and the Ophio- 

 glossacete. The axillary sporaagism of the Lycopodiacese is also a case 

 of antisporangism reduced to its simplest form, with the production of 

 three sporanges in Psilotum, two in Tmesipteris, and only one in Lyco- 

 podium, Selughiella, and Phylloglossum. The axillary sporangism of the 

 Isoeteee is derived directly from the antisporangism of Ophioglossiim. 



The antispermism of the Gymnosperms is manifested in Salishuria, 

 in the archaic Sciadopitys, and in the AbietinesB, Cupressineee, Arau- 

 carieae, and Podocarpete, but with a singular difterence of development 

 in the median and the two fertile portions of the carpid. In the 



* Ber. Deutsch. Bot. GeselL, vii. (1889) pp. 143-51 (1 pi.)- 



t Malpighia, iii. (1889) pp. 129-33. % T. c, pp. 97-lUU. 



