300 ME. A. S. HOENE— A CONTEIBUTIOX TO 



genera vvliere the ovule in the uniovulate loculus or ovary is basal. In the case of 

 Jufflans regia, already cited, the ovule, X\'hen parietally borne, is supplied by the bundle 

 in the corresponding placenta, as in Aralia ; but when basal (axially situated), bundles 

 from both placentee are contributory as in Cornus. 



OvuLAK Vascular System. — Integumentary vascular tissue has been known since 

 1829, when Mirbel * described and figured the vascular systems of the ovules of Myriea 

 pensylvanicay Corylus Avellana^ Juglans regia^ and Qiiercus Rohur, and states : — *' On voit 

 frequemment a la superficie de la Primine des nervures tantot simples tantot ramifiees 

 qui partent de la chalaze et se dirigent vers TExostome." A.' Gris f , in 1861, fi.gured 

 integumentary bundles in Bicmus communis ; Van Tieghem J, in 1872, indicates several 

 examples selected from different families, and Le Monnier §, in the same year, described 

 and figured the nervation in many seeds. The vascular system in Myriea, Juglans, and 

 certain Amentifcrse was rediscovered by E. M. Kershaw |1 in 1909. 



Balfour^ suggested that in non- vascular seeds the integument forms the water- 

 supply of the ovule. 



L. S. Gibbs** subsequently showed that the outer integument in the Alsinoidese 

 actually performs this function. 



The writer ft explained that in Davidia the ovular bundle branches and forms a 

 considerable system in the young seed, and the " integument " with its vascular 

 system is organized as an elaborate reservoir during the accumulation of an abundant 

 endosperm. 



The water problem has to be solved in connection with seed-development from ovules 

 of numerous types, and it is clear that a similar device is adopted time and again in 

 j)hylogeny, early or late in ovular development according to special needs. Hence the 

 possession of a vascular supply is scarcely of considerable phylogenetic importance, as 

 suggested by E. M. Kershaw. 



cr 



Phtlogeny op Angiosperms. — The author of each great system has in turn realized 

 that his classification is far from perfect and contains speculative groups difiicult to 

 define. Hence the finding that two families of Angiosperms are polyphyletic, in itself, 

 merely corrects or modifies a fragment of Engler's system, and, indeed, Engler 

 has already recognized the polyphyletic nature of his original Cornacese by adoptii 

 Wangerin's not satisfactorily established arrangement in * Das Pflanzenreich.* But the 

 facts that have influenced the writer to deduce polyphyletic origin for these families 

 are derived from an investigation in detail as yet unattempted, except perhaps in the 



♦ ilirbel in Mem. de I'Acad. des Sciences, ix. (1830) 632. 



t A. Gris in Ann. Sci. Nat., Bot. 4"^^ g^r. xv. (1861) 6-9, t. 2. 



4- 



5m> 



§ G. Le Monnier in Ann. Sci. Nafc., Bot. S^e g^r. xvi. (1872) 1^33-305 



Ij E. M. Kershaw in Ann. Bot. xviii. (1909) 353, 692. 



IT I. B. Balfour in Proc. Brit, Assoc. Adv. Sci., Bot. Sect. (1901). 



*♦ L. S. Gibbs in Ann. Bot. xxi. (1907) 25-55, t, 5, 6. 



ft A. S. Home in Trans. Linn, Soc, 2nd ser. Bot, yii. (1909) 315. 



