INVERTEBRATA, CRYPTOGAMIA, MICROSCOPY, ETC. 911 



tropous ovules than in those with parietal placentation and a Bmall 

 number of pendent anatropous ovules, or in unilocular ovaries with a 

 single erect ortbotropous ovule. In almost all cases the pollen-tube 

 has to traverse a longer or shorter free space between this conducting 

 tissue, where it is in the immediate proximity of the placenta, and 

 the micropyle of the ovule ; and the cause of this deviation of the 

 pollen-tube from its previous course is altogether unknown. The 

 conducting tissue of the placenta is frequently raised in the form of 

 more or less prominent papillae or hairs ; and the same is the case 

 with that of the stigma and even of the style. 



The style may be either hollow in the centre, the cavity being 

 then lined by the conducting tissue, or it may be solid, the central 

 portion being then loose and large-celled, and forming itself the 

 conducting tissue. Most commonly ovaries with parietal placentation 

 are terminated by a hollow style. In plurilocular ovaries with axile 

 placentation, there are frequently a number of separate stylar canals 

 corresponding to the number of loculi. 



The cells which form the conducting tissue do not always remain 

 united into a compact continuous tissue ; those which line the stylar 

 canal frequently become detached over a smaller or larger extent of 

 the surface, and produce a kind of soft jelly. The cells of the con- 

 ducting tissue frequently contain starch, oil, and amorphous chloro- 

 phyll. The pollen-tube traverses the style either within the conducting 

 tissue, or in immediate contact with it, or with its papillaj, drawing 

 its nutriment from its cells. The stigma, even when apparently ter- 

 minal, is always really lateral, and formed from the edges of the car- 

 pellary leaf rolled over and meeting. In the same manner there 

 is a double fprmation of conducting tissue for every carj)el within 

 the ovary ; and in those cases where the style is solid, it is formed 

 by the coalescence of the opposite edges and sides of a primitive 

 canal. 



Seminal Integuments of Gymnosperms.* — M. Bertrand publishes 

 an exhaustive paper on this subject, in which he sums up the present 

 state of our knowledge under the following heads :— 



(1) Ovules of Gymnosperms. He here discusses the orthotropy 

 of the ovules of Gymnosperms ; the number of their integuments ; 

 their development ; their " pollen-chamber " ; their vascular system ; 

 and the morphology of their different parts. (2) The transformation 

 of the ovular into seminal integuments ; including the closing of the 

 micropylar canal ; the formation of the membranous seminal integu- 

 ments ; the formation of the partially fleshy and partially woody, or 

 partially dry and partially woody integuments ; and the arillus. (3) 

 The disposition of the seminal integuments in the principal genera of 

 Gnetaceae, Coniferae, and Cycadeae. (4) The accessory envelopes and 

 disseminating organs of the seeds of Gymnosperms. This includes 

 an account of the accessory envelopes in Welwitschia, Ephedra, Gnetum, 

 Coniferfe, and Cycadeae ; and of the direct and indirect organs of dis- 

 semination in the various families. The paper is illustrated by six 

 plates. 



V * ' Ann. Sci. Nat. (Bot.),' vii. (1879) p. 61. 



