136 THE MARATTIAI.ES 



was probably a single initial in the stem and in the primary root, and Farmer also 

 thought that a single root initial was always present in Angiopteris, but concluded 

 that such ;m initial cell was not present in the stem of the young sporophyte. Breb- 

 in i i Brebner 2) says that in Dancea simplicifolia such a single initial cell seemed 

 to be always present in the stem, and my studies on Angiopteris, Kaulfussia, and 

 Danan indicate that a single initial is developed ;it an early period in the stem apex 

 and persists until the sporophyte has developed several leaves. 



Before any division occurs in the embryo the fertilized cell increases markedly 

 in size, aftei which there is formed the horizontal basal wall (rigs. 106, 109, l> b). 

 This is probably followed at once by the median wall (except in Datura), so that the 

 embryo at this stage is divided into four approximately equal quadrants (see fonk- 

 mann 3, tig. 9). 



The genus Danaa, at least this is true for D. jamaicensis and /). elliptica, 

 differs in the early divisions of the embryo from the other Marattiaceae. The egg 

 cell after fertilization elongates in a way which closely resembles that found in 

 Botrychium obliquum ( Lyon I ). I he primary hypobasal cell either divides no further 

 or only once and forms a short suspensor, so that all the organs of the young embrj 0, 

 including the foot, are really ot epibasal origin. As yet no trace of such a suspensor 

 has been found in the other Marattiaces?. 



THE EMBRYO OF MARATTIA. 



Luerssen (Luerssen 2) found the one-celled embryo and young plants of 

 Marattia cicutafoha, but was not able to procure the older embryos. The writer 

 (Campbell 3) succeeded in procuring several stages of the embryo in Marattia 

 douglasii, and somewhat later Luerssen described and figured some of the earlier 

 stages in M. fraxinea and M. weinmannttefolia. I hese, so far as I am aware, 

 complete the list of records upon the embryo of Marattia. 



The fertilized ovum in Marattia douglasii becomes much enlarged before it 

 divides and completely fills the venter of the archegonium. The granular contents 

 of the egg cell become evenly distributed without any apparent increase in quantity 

 as the fertilized ovum grows, so that the one-cell embryo contains comparatively 

 little granular contents, but the nucleus is ver) conspicuous. At the time of tin- 

 first division the young embryo is almost perfectly globular in form. I was unable 

 to find the stages immediately following this, but fonkmann has figured an eight- 

 cell embryo of M. fraxinea (see Jonkmann 3, fig. 9). The basal wall is transverse 

 and this is followed successively by the median and transverse walls, so that the 

 globular embryo is divided into approximately equal octants. From the hypobasal 

 half, which is nearest the archegonium, there is developed the foot alone, while all 

 of the other organs arise from the epibasal portion, which is turned away from the 

 archegonium. 



The youngest embryo (except tin- one-celled stage) which I found in \/. 

 douglasii, is slmwn in fig. \oh,A. This is about the same stage as the one shown in 

 fonkmann's figs. 11 and 13. Unfortunately this embryo was rather badly shrunken 

 in the process of embedding and the division walls were a good deal distorted, so 

 that it is rather hard to determine exactly their correct relation to each other; but 

 probably tin- wall b b represents the basal wall and tn the median wall. The 

 embryo has now lost its original globular form and become oval, the long axis lying 

 transversely. The secondary divisions in the octants are mostly anticlinals, and the 

 first periclinals have just appeared in a few of the cells. Figure 106, A, shows two 

 consecutive median sections. It will be seen that cell division is more active in the 

 epibasal portion than in the hypobasal region. 



