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I02 THE SCOTTISH BOTANICAL REVIEW 



assert positively that parthenogenesis really occurs in 

 Aglaonema. 



Each pistillate flower consists of a single carpel made up of 

 a somewhat depressed, nearly globular ovary, and a very large 

 stigma which is a nearly flat disk or may be slightly funnel- 

 shaped. No style is developed. A section of the young 

 carpel is shown in PL I. fig. i. Within the ovarian cavity 

 is a single large ovule arising from the base of the cavity, 

 and almost sessile. The basal portion of the ovule is very 

 massive, while the nucellus is relatively small. The stigmatic 

 surface is covered with elongated papillae, which become 

 shorter towards its margins, and in the centre of the stigma 

 is the opening of a short canal, also lined with papillae, leading 

 to the ovary. 



The form of the young ovule is much alike in all the 

 species that were studied. The funiculus is very short and 

 thick, and the ovule is bent over so that the nucellus is 

 almost horizontal. As usual there are two integuments, 

 which are free only for a short distance. At the stage 

 fio-ured, the outer integument does not extend beyond the 

 inner one. 



The nucellus is relatively small and forms an elongated 

 cone. In the youngest forms found the embryo-sac could 

 already be recognised (PI. I. figs. 2-5). At this time the 

 young embryo-sac is an elongated cell, easily distinguished 

 by its denser contents and large nucleus, as well as by its 

 position. It is usually (fig. 4) the lowermost of an axial row of 

 cells. It is probable that there is first a sub-epidermal arche- 

 sporial cell which divides into two, an outer tapetal cell and 

 an inner sporogenous one, but no stages were found young 

 enough to show this condition. 



The further history of the sporogenous cell diff"ers a good 

 deal in the different species studied. In A. conimutatuvi 

 (Campbell, 5) it was found that often there was apparently 

 a longitudinal division of the primary sporogenous cell, so 

 that a group of cells occupying the greater part of the nucellus 

 results. These cells are probably to be considered as mega- 

 spores. The young embryo-sacs in their further develop- 

 ment show great irregularities. In several cases it looked as 

 if the definitive embryo-sac structures were the result of the 



