734 
Lee. — Observations o?i the 
close in towards the centre, the pith disappears, and the xylem strands 
are only separated by the internal phloem masses, which have now fused 
together (Diagram 3, Fig. 4). Finally, a large trachea appears in the centre 
connecting the two xylem masses, and dividing the internal phloem into 
two parts (Diagram 3, Fig. 5) which pass out right and left and join on 
to the external phloem. The simple diarch condition seen in Diagram 3, 
Fig. 6, is thus obtained ; and the transition is according to Type 3 of 
Van Tieghem. 
Atropa Belladonna , L. This species was also investigated by Gerard 
( 7 , p. 377) and by Lamounette ( 12 , p. 21 1). The latter, however, described 
the internal phloem as being quite distinct from the 
external phloem even at the base of the hypocotyl. 
The present observations agree with those of Gerard. 
The seedlings are larger than in Nicandra physaloides, 
but the transition is almost identical in the two 
species. In view of the statements by Lamounette 
it should be emphasized that, before disappearing, 
the internal phloem is in direct connexion with the 
peripheral phloem groups. In many cases, at one 
stage there is no line of demarcation between the 
internal and external phloem systems (Diagram 4). 
Solatium guineense (Garden form of V. nigrum). 
Transition exactly as in Atropa Belladonna , i. e. Type 3. 
Solatium nigrum. From the description by Lamounette ( 12 , p. 21 1), 
the seedling anatomy of this species is identical with that of his Atropa 
Belladonna , i. e. Type 3, with internal and external phloem systems quite 
distinct. 
The genera Solatium , Capsicum , and Lycopersicum were investigated by 
Dangeard ( 5 ), and in the main the transition resembles that given above for 
A tropa Belladonna. 
Datura Stramonium , L. This species was first investigated by Gerard 
( 7 , p. 375), with whose description the following agrees, except in one or 
two details. The genus was also generally referred to by Lamounette (12, 
p. an). 
The fairly large seedling has two fleshy, slightly unequal cotyledons, 
with swelling at point of attachment, but without any signs of a cotyledonary 
tube. The lamina, which passes gradually into the short petiole, has a 
definite midrib with slender branches which end near the periphery of the 
leaf. The mesophyll shows the usual differentiation. 
In the lamina the midrib consists of a triangular mass of tracheae with 
the protoxylem at the upper apex, surrounded by phloem, the upper (‘ in- 
ternal ’) part of which disappears near the apex of the cotyledon. All 
except the smallest branches are bicollateral in structure (Diagram 5, Fig. !)• 
Diagram 4. Atropa 
Belladonna. In the 
hatched portion the 
phloem cannot be dis- 
tinguished from the 
ground tissue. 
