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c. 
MR. R. H. COMPTON : AN INVESTIGATION OF THE 
THE LEVEL or THE TRANSITION. 
In the summaries of the characteristics of different sub-orders and tribes. 
reference has repeatedly been made to the correlation which exists between 
the level of the transition and the dimensions of the seedling. A connection 
of this kind has been indicated by certain authors, in particular by Gérard 
(1881, p. 298), who states: “ Il y a une certaine rélation, non absolue pourtant, 
entre le volume de la plantule et la rapidité du passage. Si le diamètre du 
végétal est étroit, la structure de la tige peut ne s'observer qu'à la base du 
premier entre-nceud aprés le départ des cotylédons. ... . Il est fréquent de 
rencontrer chez les plantules volumineuses la structure de la tige dans une 
partie de la tigelle." It is rare, however, to find measurements included in 
the descriptions of seedling-structure given by earlier writers, and it is now 
possible for the first time to give numerical expression to the relation between. 
size and structure in the Leguminose. 
In this paper transitions are classified roughly according to level, as low, 
intermediate-low, intermediate, intermediate-high, and high (see p. 66). In 
the Summary List the facts for the level of transition are displayed side by 
side with the measurements of length and diameter of the hypocotyl and the 
dimensions of the cotyledons. (There will be little said about the size of 
cotyledons, and the data are included chiefly for the sake of completeness.) 
It is thus a matter of arithmetic to find the average diameter and length 
of hypocotyl for each of the five classes of transition. The results of the 
calculations are given in the following table :— 
| | 
| I IL | Hl. IV. Ve VL 
| | Average diameter of | 
| hypocotyl Average 
2. | Avernge UTI _ | volume of | 
Level of Transition. Numter of | length of | | hypocotyl, | 
Species. hypocotyl | At base | At summit iL R+r\?) 
ш. | QR. | (Q2 | ( 2 J| 
— — — EM 
m ME 30-32 407 9:5 | 969 | 2296 | 
о ( Intermediate-Low. .. 21 | 96:0 1:30 109 | 975 
= 4 Intermediate ...... | 21 | 22 | тә — 101 | 90-9 
Mel А | | | | 
^^ [ Intermediate-High . 10 |, 209 116 | 102 | 193 | 
Middle (total). .....| 52 ' 2331 195 | 102 | 236 
High EE | 84-896 16:5 O85 O75 | 83 
| | | 
In column I. is given the class of transition-level. In column П. is placed 
the number of epigeal species recorded in the Summary List from which ihe 
