DORETY—MICROCYCAS CALOCOMA 147 



formation 



Fig. 30.— Detail from jig. 3 showing one of the four 

 loint of insertion. X60. 



Fig. 4.— Base of the cotyledonary trace shown in jig 

 Fig. 45. 

 imngement. 



Fig. 5.— Exit of lateral root. X60. 

 Fig. 6.— Diagram of root stele. 

 Fig. 6a.— Detail of one of the root poles. X60. 



Fig. 7.— Transverse section of the central vascular system above the coty- 

 fcdooary node. It is composed of four groups of leaf traces. Semidiagrammatic. 



Fig. 8.— Longitudinal section of portion of girdling leaf trace taken from 

 transverse section of cppHlino* v<^ 



PLATE VI 



Fig. 9. Transverse section of median traces of same leaf from same section 

 «fr*. X380. 



Fig. 10.— Transverse section of leaf trace slightly above that represented in 

 «• 9- X380. 



ig. 11 — Transverse section of same bundle 60 m above section represented 

 m k- 10. X380. 



Fig. 



12. 







Exarch bundle from petiole 8 mm from base. X 380. 



fas'onV I '~ Transverse action of embryo, showing the sheath formed by the 

 ^0 the cotyledonary petioles, the increase in the number of leaf traces in 



Kttwe leaves, and their gradual assumption of the O arrangement. X8. 



■"'n ! 4 '~ Transverse section of three leaves in their natural arrangement, 

 ? he relative amount of centrifugal wood at different levels of the petiole. 



showi 

 X8. 



Fir 



Fic ^~ App . roach of two kaf traces. X380. 



cwtonl- . ' US1 ° n of some of the xylem elements of same to form a quasi- 

 ^tnc strand. X380. 



Unni n eels ~V °5u° n ° f periphera l re g ion of tissue of petiole showing position of 



r IG ig -^T" r 



J P ol young pinna showing unicellular hairs or ramentum. X 760- 



