Bowenia spectabilis , Hook. f. 489 
Figure 1 was prepared ; and to Dr. D. H. Scott, to whom 
I am indebted for valuable advice on several points that have 
arisen during the course of the work. 
The Botanical Laboratory, Cambridge. 
EXPLANATION OF FIGURES IN PLATES 
XXVII AND XXVIII. 
Illustrating Mr. Pearson’s paper on Boivenia. 
The following is a list of the abbreviations used: a. g., apogeotropic root; 
a. ph }, secondary phloem of apog. root ; a. xy }, secondary xylem of apog. root ; 
c., cork; cb., cambium; cf. xy., centrifugal xylem; cp. xy., centripetal xylem; 
cx., cortex; d. e., depleted endosperm cells; e., endosperm; end, endodermis; 
ep., epithelial layer of cotyledon ; f cot., fused cotyledons ; fb., fibres ; g., stoma ; 
i. c., intercellular spaces, containing Anabaena ; m. c., mucilage canal ; m.r., primary 
medullary ray; m.r}, secondary medullary ray; p. ph., protophloem; p. xy., 
protoxylem ; p., papillose layer of apogeotropic root ; ph}, secondary phloem ; 
pL, phellogen ; pc., pericycle ; s., seed ; s. c., stone cell ; s. t., sieve-tube ; st., petiole 
of cotyledon; se., stereome ; t., testa; v. b., vascular bundle; xy}, secondary 
xylem. 
Fig. 1. Drawing of a young plant, seven months old, § natural size. 
Fig. 2. From a photograph. An apogeotropic root, x 2. 
Fig. 3. Diagram of a median longitudinal section through the seed at the stage 
shown in Fig. 1. 
Fig. 4. Transverse section of the vascular bundle in the cotyledon, x 180. 
Fig. 5. From a photograph. Transverse section of the stelar region of the main 
root of a young seedling, x 60. 
Fig. 6. Diagram to illustrate mode of secondary thickening in the root. ^ 
Fig. 7. Portion of a transverse section of the root, to show the structure of the 
secondary phloem, x 140. 
Fig. 8. Diagram to illustrate mode of origin of the apogeotropic root. 
Fig. 9. Portion of transverse section of the vascular bundle of the stalk of the 
apogeotropic root. x 180. 
Fig. 10. Portion of transverse section of the ‘head’ of the apogeotropic root 
showing the papillose layer, x 70. 
Fig. 11. Portion of transverse section of the stalk of the apogeotropic root, to 
show position of the 1 Anabaena- layer.’ x 68. 
Fig. 12. Ditto, x 180. 
L 1 2 
