514 BOTANICAL GAZETTE [june 



structures. Strasburger (35) described the bundle supply to 

 the three pairs of decussate scales and to the ovule, accepting 

 Van Tieghem's interpretation of the situation. Later he reversed 

 his earlier view and regarded the ovule as terminal, there being 

 nothing in the course of the bundles to give a clue to the lateral 

 position of the ovule. He described the bundles in the integument 

 as consisting of long, thin-walled elements, but containing no 

 tracheids. Miss Aase describes the vascular supply to the ovule 

 and the fusion in pairs of the four bundles from the axis as different 

 from cases in which the united bundle is to supply an axillary 

 structure, the pair consisting of "one bundle from each side of the 

 bract bundle of the next lower pair, and not one from each side 

 of the bract of the last pair." Miss Aase also pointed out the con- 

 centric character of the bundles in the base of the ovule, and the 

 possible ending of one of the bundles before reaching the ovule. 

 From her study the suggestion is made that there may have been 

 a fusion of sporophylls to form a single structure, implying "the 

 reduction of the ovules to one, the complete fusion of two sporo- 

 phvlls to the integument of the ovule, and finally the reduction 

 of the vascular supply to each sporophyll to the single weak bundle 

 in the wing of the ovule." She concludes, however, that "further 

 investigation is necessary." 



In T. canadensis the essential facts are not materially different 

 from those of T. baccata, and a brief statement of the situation will 

 be sufficient. The secondary axis receives two large bundles from 

 the cylinder of the primary shoot (figs. 21, 44), these uniting at 

 their edges and forming a closed cylinder (fig. 45). The traces 

 to the first pair of scales are given off near this level (fig. 46). 

 Traces are then given off to the second pair of scales (fig. 47), above 

 which the gaps formed by the first pair of traces are closed, giving 

 again two large bundles in the cylinder (fig. 48). The bundles to 

 the third pair of scales are given off directly above those to the 

 first pair (fig. 40), these bundles being usually quite short, at times 

 not even reaching to the scale, but ending in the cortex itself. The 

 main cylinder now consists of four bundles, two on each side, the 

 pairs being separated by the gaps formed by the third pair of scale 

 bundles. The two bundles of each pair turn through an angle of 

 45 and unite laterally (fig. 51), closing the gap formed by the second 



