Davey — Seedling Anatomy of certain A mentiferae. 577 
It will bd remembered that there exist two modifications of the 
Cruciform type : the tetrarch as described for Althaea rosea and many 
Rosales , 1 and as occurring also in Leguminosae , 2 Cactaceae , 3 Tubiflorae , 4 
&c., and the diarch as described for Ranales and Rhodadales, and for 
many other cohorts * 5 In the former case four root poles are present, two in 
the cotyledonary and two in the intercotyledonary planes respectively, 
while in the latter case only the cotyledonary poles are present. Examples 
of both the above types have been found among the Amentiferae to be 
described. 
In the Diagonal type the root poles occur in planes lying between the 
cotyledonary and intercotyledonary planes. The following diagonal modi- 
fications known to exist in other groups 6 occur relatively frequently in the 
Amentiferae : diagonal tetrarchy (e. g. Alnus cor dif olid ) , hexarchy, in which 
the preceding modification is combined with cruciform diarchy (e. g. Quercus , 
Castanea ), octarchy, a combination of cruciform and diagonal tetrarchy 
(e. g. Cary a ainard), and in addition a double diagonal octarch type in 
which eight xylem centres occur on diagonals lying in pairs between the 
cotyledonary and intercotyledonary planes (Fig. 1, a, b, c , d). 
This diagonal octarchy appears to be of constant occurrence only in 
Fagus sylvatica. It is shown by some individuals of Quercus Ilex , and has 
been described by Miss W. Smith 7 in a seedling of Palaquium petiolare , 
a member of the Sapotaceae. 
In the published accounts of other groups the greater number of forms 
are shown to possess one or other modification of the cruciform type, diarchy 
being by far the most common. The diagonal type is rare, but has been 
described in Calycanthaceae and in Rosaceae by Dr. Thomas, in Sapota- 
ceae by Miss W. Smith , 8 and in Ebenaceae by Mr. Wright . 9 
In the Amentiferous forms herein dealt with (exclusive of the Piperales 
and Urticales), diarchy is comparatively rare* since it is found only in the 
Salicales and in Betula and Alnus among Fagales. In the remaining forms 
cruciform tetrarchy and the various diagonal modifications occur with 
about equal frequency. Diarchy would seem to be the characteristic type 
1 Thomas, E. N. i loc. cit., p. 698. 
2 Compton, R. H. : Seedling Structure in Leguminosae. Journ. Linn. Soc. Bot., vol. xli, 1912. 
3 de Fraine, E. : Seedling Anatomy of certain Cactaceae. Ann. of Bot., vol. xxiv, 1910. 
4 Lee, E. : Seedling Anatomy of certain Sympetalae. Pt. I. Ann. of Bot., vol. xxvi, 1912. 
Pt. II. Id*, vol. xxviii, 1914. 
5 Hill, T. G. : Piperales, loc. cit. Hill, T. G., and de Fraine, E. : Seedling Structure oi 
certain Centrospermae. Ann. of Bot., vol. xxvij 1912. Chauveaud, G. : L’Appareil conducteuf 
des plantes vasculaires. Ann. Sci. Nat., Bot., 9® ser., t. xiii, 1911. 
6 Thomas, E. N. : loc* cit., p. 698. 
7 Smith, W. : The Anatomy of some Sapotaceous Seedlings. Trans. Linn. Soc., ser. ii, Bot., 
vol. vii, 1909. 
8 loc. cit. 
9 Wright, H. : Genus Diospyros in Ceylon. Ann. Roy. Bot. Gard., Peradeniya, vol. ii, pt. 1, 
1904, pp. 62-5. 
