248 SUMMARY OF CURRENT RESEARCHES RELATING TO 



bundles; it is produced by a division of the internal layers of the 

 cortex and cells of the pericycle and the pith ; it forms immediately a 

 meristematic zone outside the primary formations, and new swellings 

 are formed by a lateral extension of this zone with production of a new 

 bud. In the case studied by the author the structure of the cotyledons 

 was peculiar ; the axis was arrested at the summit of the tubercle, the 

 cylinder which supported the cotyledons with its two bundles only 

 represented a sort of sheath, the axis being replaced by a central 

 lacuna. 



Morphology of the Mistletoe.* — Dr. S. Schonland has observed a 

 large number of abnormalities in the structure and arrangement of the 

 organs of the mistletoe, many of which have been noticed before, while 

 others are apparently new. The present paper deals with the mor- 

 phology of the flowering shoots, including both the arrangement and 

 general structure of the flowers. The mistletoe is dioecious. The plants 

 of the two sexes have on the whole the same structure. The inflo- 

 rescences are usually found between the two foliage-leaves, and nor- 

 mally consist of two lateral flowers at right angles to these leaves, and 

 a terminal flower. The terminal flower of the male inflorescence is, as 

 a rule, not preceded by scale-leaves. But Hofmeister has stated that 

 they are present here, as in the female. This is really often the case, 

 although not observed by-Eichler; but still the structure of the inflo- 

 rescences in which it occurs is not the same as that of the female 

 inflorescences, and this apparent abnormality can be observed in inflo- 

 rescences developed from dormant buds. In the female flowers the 

 perianth usually consists of two dimerous alternating whorls of scale- 

 leaves, which cohere more or less at the base. An increase in the 

 number of parts composing the male terminal flowers is not rare. 

 Eichler only knew of pentamerous and hexamerous flowers besides the 

 normal ones ; the author, however, has observed one heptamerous and 

 one decamerous flower. 



Structure of Marcgraviaeese.t — Herr H. 0. Juel gives details of 

 various points of structure in the plants belonging to this tropical 

 natural order, especially oi Marcgravia polyantha and Norantea brasiliensis, 

 both from Brazil. 



The outer bark contains a close tissue, supported by stereides ; in 

 the inner bark there are no mechanical elements. There are no tracheides 

 in the wood ; the wood-fibres are septate, and have narrow fissure-like 

 slightly bordered or larger elliptical pits. In the nectaries the secreting 

 tissue is formed from the fundamental tissue, and is covered by a thin 

 epiderm without stomates. The gamopetalous corolla is composed of 

 four leaves alternating with the sepals. The outer integument of the 

 ovule is shorter than the inner one, and the embryo-sac is near to the 

 micropyle. When the seed is ripe the end of the inner integument 

 projects beyond the testa, the outer integument forming the single hard 

 layer of the testa. The embryo is surrounded by a layer of cells, the 

 outermost endosperm-layer ; and in Norantea there are also the remains 

 of a starchy endosperm, In Marcgravia some of the seeds are sterile, 

 without embryo. 



* Ann. of Bot., ii. (1888) pp. 283-90 (1 pi.). 



t Bih. K. Svensk. Vet.-Akad. Handl., xii. (18S7) No. 5, 28 pp. and 3 pis. Cf. 

 this Jotu-nal, 1888, p. 449. 



