XX] 



EMBRYOLOGY 



which possess it are in this respect archaic. Many instances might be quoted 

 where a vestigial part is inconstant in its occurrence, in the genus, species, 

 or even the individual. Accordingly those embryos which possess a suspensor 



Fig. 412. Embryos of Marattiaceae, all orientated with the archegonial neck down- 

 wards, as in nature. a = Angiopteiis : b= Christensenia : c — Marattia: d, e = Danaea 

 janiaicensis: j-?w = suspensor : j/ = stem: t-o/ = cotyledon :/= foot : (^, A = basal wall. 

 (All after Campbell.) 



FiCT. 413. Embryos ol Macroglossum after Campbell, showing the 

 natural orientation, and the relation of the suspensor to the 

 archegonium. 



are here held to be relatively primitive in respect of that feature, while 

 those without it are held as relatively advanced. The Ophioglossaceae and 

 Marattiaceae are the only two families of Ferns in which this organ has 



