On the Embryo of Welwitschia. 1 
BY 
H. H. W. PEARSON, Sc.D., F.L.S. 
With Plate LXIV and two Figures in the Text. 
^ account of the development of the proembryo of IVehvitschia up to 
±~\. the stage represented in the diagram (Text-fig. i) has been given in 
a former paper. 2 In this condition the proembryo consists of a suspensor 
and a terminal cell-group. From the latter have been formed twenty-four 
of the twenty-five cells of which the suspensor consists ; it also gives rise to 
Text-fig. i. Diagram of an almost median longitudinal section through the distal end of 
the pro-embryo of Welwitschia at the stage figured in Pearson, 1909 A, PL 30, Fig. 85. 
/. s. ) 1 primary ) 
i. c. r. > = } inner cortical ring > cells of the suspensor (cf. Pearson, l.c., Fig. 87). 
0. c. r. ) l outer cortical ring ) 
e. = 3 of the 8 cells of the ‘ presumed embryonic plate ’ (cf. Pearson, 1. c., Fig. 86 b). 
x. — 2 of the 16 cells of the ‘ lower ring ’ (cf. Pearson, 1. c., Fig. 86 b). 
c. = 4 of the ‘ cap ’ cells (cf. Pearson, 1 . c., Fig. 86 a). 
the embryo itself. The terminal group at this stage contains (1) eight 
or more ‘cap ’ cells (Text-fig. 1 ,c .); (2) a ring of sixteen peripheral cells just 
below the suspensor—the 4 lower ring ’ (x.) ; this surrounds (3) an internal 
plate of eight cells, the 4 presumed embryonic plate * ( e .). 
This was the latest stage found in material collected in Damaraland 
between January 21 and February 1, 1907. As it was seen many times it 
seemed possible that further development was preceded by a resting period- 
1 Percy Sladen Memorial Expedition in South-west Africa, 1908-1909, Report No. 3. 
2 Pearson, 1909 a, pp. 364-368. 
[Annals of Botany, Vol. XXIV. No. XCVI. October', iqio.] 
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