194 
Hill and de Fraine. — On the 
clearly that of a half-cotyledon, and the bundle c , although it first behaved 
as the strand of a whole cotyledon, finally performed as that of a half- 
cotyledon. 
Abies fir ma > Sieb. and Zucc. One seedling only was available for study. 
It had four cotyledons, and the transition-phenomena closely resembled 
those described for A. balsamea. The rotation of the xylem was more 
strongly marked in A.firma than in A. balsamea . 
Abies sachaliensis, as far as our inadequate material indicates, is 
essentially similar to A. jirma. 
Abies pectinata , DC. The usual number of cotyledons is eight, which 
Diagram 2. Abies pectinata. 
in some cases form a short tube. The root is triarch in structure, which 
arrangement is arrived at in two different ways. 
In the first case, the eight seed-leaf-traces form a well-marked zone in 
the upper part of the hypocotyl ; rotation then takes place, the protoxylems 
of two adjacent bundles are thus brought into contact and gradually assume 
the exarch position, concurrently the eight phloem masses fuse in pairs. 
The inward rotation of the metaxylem still continues until the fusion of 
each pair is completed, and hence a tetrarch root-structure results. At 
a lower level a triarch arrangement supervenes by the obliteration of one 
xylem group and the fusion of the two lateral phloem masses (Diagram 2, 
Figs. 1, 2 and 3). 
