ii8 ROBERT BROWN 



authors he cites. He emphasises the need of studying the 

 development in order successfully to interpret the mature struc- 

 ture. He insists on the origin of the seed coats from the 

 integuments, on the orientation of the embryo within the amnios 

 (embryo sac), and on the distinction between the true albumen 

 which is contained in this " amnios " and the albumen " formed 

 by a deposition of granular matter in the cells of the nucleus " 

 (nucellus), i.e. the perisperm, and he goes on to suggest that in 

 some of these cases the " Membrane of the amnios seems to be 

 persistent, forming even in the ripe seed a proper coat for the 

 embryo.... This is the probable explanation of the structure of 

 true Nympheaceae"...here he seems to have overlooked the 

 rudimentary endosperm which is really present. Finally he sums 

 up an admirable account of the whole matter as follows : " The 

 albumen, properly so-called, may be formed either by a disposi- 

 tion or secretion of granular matter in the utriculi of the amnios, 

 or in those of the nucleus itself, or lastly that two substances 

 having these distinct origins and very different textures may 

 coexist in the ripe seed as is probably the case in Scitamineae." 



He then goes on at once to argue that the apex of the 

 nucleus is the point of the ovulum where impregnation takes 

 place, and adds that " all doubt would be removed if cases could 

 be produced where the ovarium was either altogether wanting 

 or so imperfectly formed that the ovulum itself became directly 

 exposed to the action of the pollen or its fovilla." This leads 

 him at once to enunciate his view of the gymnospermy of Cycads, 

 Conifers and Gnetaceae. He reviews very fully the opinions that 

 had been expressed by others as to the real structure of the 

 female organ, especially of Pinus, and he mentions the fact that 

 he himself in the botany of the Flinders' voyage had previously 

 held the view that a minute perianth was present in the Pine, a 

 view which, as he says, " On reconsidering the subject in con- 

 nection with what I had ascertained respecting the vegetable 

 ovulum " he had now abandoned. 



The morphology of the male sporophyll of Cycas, however, 

 presents a great difficulty, and Brown, less fortunate here, 

 discusses a number of what seemed to him possible explana- 

 tions. The recognition of Sporangia was remote, and the effort 



