xxxtv] 



CAEDIOCARPTJS 



339 



afforded by the course and place of origin of the lower vascular 

 strands from the main supply at the base of the seed. The outer 

 vascular system consists of two bundles given off from the main 

 strand, before it reaches the sclerotesta, which pass up the sarco- 

 testa (fig. 500, B). In Rhabdosper'mum, on the other hand, the 

 corresponding bundles arise at a 

 higher level and form recurrent 

 strands which penetrate the 

 sclerotesta before passing up the 

 fleshy part of the integument 

 (cf. fig. 501, E). 



Cardiocarpus sclerotesta Brong- 

 niart. The testa is differentiated 

 into an inner shell and an outer 

 sarcotesta (fig. 501, A ; the sclero- 

 testa is shown in black) ; there 

 is a well developed pollen- 

 chamber (pc) and below this the 

 prothallus-tissue is prolonged as 

 a blunt and short tent-pole, b, 

 as in Gingko and in several fossil 

 seeds. On each side of the apical 

 tent-pole the shghtly shrunken 

 prothallus shows two small 

 archegonia, a, which in the rela- 

 tively small size and spherical 

 form of the egg-cells resemble 

 those of Ginkgo. In transverse 

 section (fig. 501, B) the seed is 



bi-convex and at each end of the major axis the sclerotesta forms a 

 small keel. There are two sets of vascular bundles concerned in the 

 supply of material to the ovule ; a lower pair of bundles given off 

 from the central strand in the sarcotesta (fig. 500, B) which pass 

 to the apical region in the inner tissues of the sarcotesta in the 

 principal plane (fig. 500, A, v), and an inner set of bundles that 

 pass up the peripheral tissue of the nucellus. 



The species described by Brongniart as Cardiocarpus (Cyclo- 

 carpus) tenuis and C. nummularis have been removed by 



22—2 



Fig. 500. Cardiocarpus drupaceus var. 

 expansiis. A, transverse section of 

 the testa approximately in the middle 

 of the seed; v, vascular bundles. 

 B, diagrammatic sketch, adapted 

 from Brongniart's drawing of the 

 base of the seed showing the sarco- 

 testa, aa, the sclerotesta, sc, and the 

 pad of vascular tissue, d, at the base 

 of the nucellus. (After Brongniart. ) 



