620 BOWMAN— ECOLOGY AND 



plete series were lacking in his studies owing to deficiency in ma- 

 terial. In this resume, the rather specialized paper by Haberlandt^* 

 and to some extent the studies of Johow^^ cannot be overlooked. 

 The former was particularly concerned with the nourishment of the 

 embryo and the function of the endosperm. 



In this paper the embryology has not been considered as being 

 of primary consideration in relation to the studies of the physiology 

 of the species and in view of the investigations already made on 

 the embryology the main features will only be reviewed here to 

 give a clearer understanding of the morphology. A few photomi- 

 crographs are given also by way of illustration. 



The ovules all show a nucellus and in the tip of this, which in 

 cross section is slightly irregular in outline, there is the arche- 

 sporium. Cook says this is subepidermal and figures it as such. 

 This archesporial cell cuts ofif two tapetal cells, but this number 

 does not appear to be definitely known for the genus. However, 

 Karsten's material R. nnicronata is figured as having two tapetal 

 cells and Cook's material R. mangle also. In the figure of the longi- 

 tudinal section given in this paper the large horseshoe shape section 

 of the integument is seen as the only one present. Cook has shown 

 that there really are two integuments at the beginning where the 

 archeporial cell is still small, but that later the inner one is destroyed. 

 The integuments both grow rapidly and soon enclose the nucellus, 

 while the archesporium divides into the megaspore cells. Here 

 there seems to be a discrepancy in the number for the genus, as 

 Karsten found four for R. mucronata, while Cook gets three for 

 R. mangle, but as Cook says he only was able to secure one good 

 preparation of this stage the constant number cannot positively be 

 stated. As the embryo sac enlarges the nucellus completely disap- 

 pears, as does also the inner integument with growth of the sac. 



This stage, or one a little later, is shown in the figure where 

 the outer integument is seen with a littte of the soft spongy endo- 

 sperm inside and the enlarged embryo, with the tiny dark area 

 where the plumule is beginning to form. The cells of the endosperm 



84 Haberlandt, G., " Ueber die Ernahrung der Keimleinge, etc.," A)in. du 

 Jardin Botantque de Buitenzorg, Treub, Vol. 12, p. 91, 1895. 

 **■'' Johow, Fr., loc. cit. 



