ZOOLOaY AND BOTANY, MICROSCOPY, ETC. 581 



BOTANY. 



A. GENERAL, including Embryology and Histology of the 

 Phanerogamia. 



Homology of the Reproductive Organs in Phanerogams and 

 Vascular Cryptogams,* — L. Celakovsky has made a fresh detailed 

 investigation of this subject. He maintains his previous view, held 

 also by Warming and Prantl, of the homology of the integuments of 

 the ovule with the indusium of ferus, as is sufficiently proved by the 

 phenomena of phyllody of the ovule, which show that the ovule is 

 due to a transformation of a segment of a fertile leaf together with 

 the nucellus or macrosporangium belonging to it ; the integuments 

 being formed from it in just the same way as the indusium from the 

 fertile leaf-tip of the Filicinese. The nucellus is formed directly from 

 the upper part of the ovular papilla ; the integument then springing 

 from its base and enveloping it ; this being followed in most cases by 

 a second envelope formed in the same way outside the first. The 

 nucellus being homologous to a sporangium, the mode of formation 

 of the ovule coincides with that of the sporiferous leaf-segment of 

 Lygodium, the sporangium of Lygodium being formed at the apex of 

 a segment of a fertile leaf, just like the nucellus on the ovular papilla, 

 and the indusium round the sporangium just like the single or 

 double integument round the nucellus. In Trichomanes the only 

 difference is that the sporangium is replaced by the sporiferous 

 receptacle. When normally dichlamydeous ovules undergo phyllody, 

 they become monochlamydeous, and form a simple stalked cup which 

 corresponds to the integuments, the stalk corresponding to the 

 funiculus. The nucellus sometimes occupies its normal terminal 

 position at the bottom of the cup, sometimes it is pushed towards its 

 rim. The segment of a fern-leaf which bears the indusium on its 

 under side corresponds to the outer ovular integument in Angio- 

 sperms. 



In the Hymenophyllacese the indusium is not formed from the 

 apex of the leaflet which corresponds to the nucellus or receptacle of 

 the sorus, but as a lateral new formation. The single terminal 

 sporangium appears to be more archaic than the polyangic sorus with 

 its receptacle. The author believes that the sexually produced 

 generation (non-sexual generation) of the first Vascular Cryptogams 

 originated from the branching of the sporogonium of a moss. The 

 sporangium of ferns is then homologous, from a phylogenetic point 

 of view, to the sporangium of mosses, notwithstanding its different 

 morphological value. The sporangium of Schiza^accaj is an older 

 stage of development, and that of Ophioglossacea) older still, where tlio 

 integuments are entirely wanting, and the sporangium is therefore 

 formed from tlie greater part of the leaflet, perfectly homologous to 

 the naked ovule of the Santalacesc, Balanophorcfc, and Crinum. 



* Pringfllifciin'H Jalirl.. f. WiHrf. Bot„ xiv. (1884) \>i). 2dl--',7H (.'{ pl8.>. 



