Hill and de Fraine. — On the 
178 
the more striking : in the former plant, as in Claytonia , the lateral strands 
of each cotyledon fuse on to the larger central bundle in the upper region 
of the petiole before any vascular rearrangement is inaugurated in the 
median bundle ; this strand, in transverse section, appears like a widely 
opened U with the xylem-elements, situated on the concave side, well 
dispersed owing to the development of much parenchyma, the presence of 
which makes it difficult to trace the movements of the protoxylem ; finally, 
no cotyledonary tube is formed. As in the majority of the foregoing plants, 
the vascular rearrangements begin in the petioles of cotyledons, but in the 
basal rather than in the upper regions. 
Lychnis Vise aria, L. The transition phenomena resemble those of 
Cucubalus ; the central bundle of each cotyledon is, however, very small in 
Lychnis and the vascular rearrangements are more ill defined. A cotyle- 
donary tube is formed. 
Lychnis Githago. According to Gerard 1 the transition follows the 
same course as in Silene inflata . 
Silene inflata follows type 3. From Gerard’s account it appears that 
the transition phenomena commence in the upper regions of the petioles of 
the seed-leaves, but at a level just above the cotyledonary node the 
bifurcated bundles again close up. This is in accordance with our 
observations on 5 . pendula. 
Silene pendula , L., shows no features of particular interest ; the 
transition follows type 3, and the bifurcation of the main cotylar strand 
begins in the petioles of the seed-leaves before all the small laterals have 
fused with it. On tracing these half-bundles downwards, they are seen 
gradually to close up so as partly to sandwich the protoxylem-elements 
between them ; thus at the cotyledonary node these bundles are closely 
apposed with the protoxylem towards the exarch position. There is 
a well-marked cotylar tube. 
Silene Otites , Sm., closely resembles S. pendula, 
Silene Schafta , Gmel ex Hohen., does not differ in any important 
feature from S. pendula. The bifurcation begins at a relatively high level 
in the cotyledons, and the lateral strands unite with the adjacent portions of 
the divided central bundles at about the same level. 
Another example showed the unusual feature of a triarch root. The 
changes which led to this were as follows. One cotyledon was normal in 
having in the base of its blade one large central bundle and two small 
lateral ones ; the other had two central ones and two laterals. The lateral 
1 Gerard : Recherches sur le passage de la racine a la tige. Ann. Sci. Nat., Bot., s£r. 6, 
t. xi, 1880. 
