688 SUMMARY OF CURRENT RESEARCHES RELATING TO 



Uvularia recall those of Gloriosa and Littonia, but they are less specialised 

 than those of the latter genera. In place of a tubercle there is a rhizome 

 and the aerial stem is upright, slender, and short as contrasted with the 

 elongated leafy stem of Gloriosa and Littonia. Corresponding with 

 these differences there are anatomical differences. Although there are 

 two kinds of leaf -traces in Uvularia, they are less clearly defined than in 

 the tuberous Uvularieae. Tricyrtis hirta is of a still simpler tyjae. It is 

 a geophilous plant with a branched rhizome ; the stem and leaf are of 

 the simplest anatomical form ; and there is only one kind of leaf- 

 trace which traverses the stem in the typical manner. It would seem 

 that Tricyrtis is nearer than Uvularia to the ancestral type of the 

 group. The tuberous Uvulariege are thus regarded as very highly 

 specialised Liliacese, the rhizotomous Uvulariege are of intermediate rank, 

 while Tricyrtis is lowest in the series. The author is of the opinion 

 that in the present state of our knowledge it is undesirable to lay too 

 much stress upon the usual definitions of primary and secondary tissues, 

 since the characters of such tissues are not constant. 



Reproductive. 



Microgametophyte of the Podocarpineae.* — E. C. Jeffrey and M. A. 

 Chrysler have studied the male sexual generation of the Podocarpinege 

 with special reference to their phylogeny. The genera Podocarpus and 

 Dacrydium show' proliferation of the two prothallial cells, which in some 

 cases is accompanied by similar proliferation of the generative cells, a 

 circumstance which has hitherto not been observed in any Gymnosperm. 

 The proliferation of the prothallial cell has, however, been observed in 

 the Araucarian genus Agathis. There is no reason to suppose that such 

 proliferations are a primitive feature. The general microgametophytic 

 development in the Podocarpineae and the Araucarinese points to a 

 common ancestral stock allied to the Abietinese. The authors regard it 

 as not improbable that the Podocarpineae and Araucarinese may be more 

 nearly allied than has hitherto been supposed. 



Pro-embryo of Pinus Laricio.f — N. J. Kildahl has studied the 

 embryo of Pinus Laricio with special reference to the development of 

 the walls. The author finds that the cross-walls are formed in the 

 usual way, and come a little in advance of the vertical walls. The 

 vertical walls are formed by secondary fibres from the nuclei of the 

 respective tiers. The formation of the first cross walls and the first 

 vertical walls is connected with the division of the first four free nuclei. 

 The second division in the basal part of the egg may occur in either tier. 

 The last division of the four nuclei is not always simultaneous. 



Pollen-lbrmation in Cucurbitacese.J — J. E. Kirkwood has studied 

 the pollen of FevilUa cordifolia, Micrcmipelis lolata, Cyclanthera explo- 

 dens, and other members of the Cucurbitacese. The development of the 

 sporogenous tissue and the pollen agrees with that of other members of 

 the family. The poUen-mother-cells are especially interesting owing to 



* Amer. Nat., xli. (1907) pp. 355-64 (5 figs.). 



t Bot. Gazette, xliv. (1907) pp. 102-7 (2 pis.). 



I Bull. Torrey Bot. Club, xsxiv. (1907) pp. 221-42 (5 pis.). 



