Seedling Structure of certain Centrospermae. 199 
structure of two seedlings of a genus which are of different sizes. Thus the 
seedling of Saponctria Vaccaria is much larger than that of cerastoides ; 
in the former plant the laterals fuse on to the central bundle of the seed-leaf 
at a much lower level than in the latter plant. Spergidaria salina and 
Spergirta arvensis , A triplex littoralis and A. thamnoides , Suaeda maritima 
and 5 . dendroides , and Phytolacca acinosa and P. dioica are further examples. 
Also it may be mentioned that amongst the smallest seedlings examined 
were those placed in Class A (par. 3), and these exhibited the simplest 
structure. These facts, together with others of similar nature observed in 
other classes — for instance, the Gymnosperms — suggest that the transition 
phenomena may depend on the relative abundance and the distribution of 
the cotyledonary vascular supply, which is in turn influenced by various 
factors. This will receive more particular attention in our next contribution 
to the subject. 
9. With regard to features of interest not directly connected with transi- 
tion phenomena, the presence of an endodermis around the cotyledonary 
bundles of certain species of Mesembryan themum may be referred to. 
In conclusion we desire to express our thanks to Mr. Hales, the Curator 
of the Chelsea Physic Garden, for his never-failing kindness in rearing seed- 
lings for our use. 
