NOTES AND ABSTRACTS. 



865 



uncommon. But the passage from cone to shoot is not, as in the present 

 case, abrupt, but gradual. Masters has shown conclusively (Gard. Chron. 

 N.S. xvii. pp. 112, 113) that in such cases the bract-scales pass into 

 ordinary foliage leaves with which they are serially continuous. The fact 

 admits of no dispute, and the interpretation is generally accepted. So far 

 we seem to be on solid ground ; whatever be the explanation of the 

 seminiferous scale, it is at any rate 1 subtended ' by the bract-scale, which is 

 undoubtedly a modified foliar organ and is not seminiferous." The author 

 then contrasts this bract-scale of the Coniferce with the seminiferous scale 

 of the Cycadece. He points out that they are homologous, and, after 

 remarks on the Gymnosperms in relation to Cryptogams and Phanerogams 

 gives an acceptable rhume of the different views that have been held by 

 chief authorities as to the nature of the seminiferous scale. The author, 

 returning to the specimen, among other remarks says : " I have already 

 noticed that the cone now described is below the normal size. It may 

 be supposed that the food-supply directed towards it was in excess of its 

 needs. The growing point was therefore started into activity. That 

 this was not, however, accomplished without a struggle is proved by the 

 deep constriction between the shoot and the cone. The passive tension 

 of the apex of the cone prevented any increase in the diameter of the shoot 

 till it was entirely free from it." — B. I. L. 



Pinus Nelsoni. By G. R. Shaw {Gard. Chron. No. 921, p. 122, 

 fig. 49, August 20, 1904).— This Pine was collected by Mr. E. W. 

 Nelson, of the United States Biological Survey, in 1898, on a mountain in 

 North- Eastern Mexico. The scales of the cones are not provided, as those 

 of most Pines are, with hygroscopic dorsal plates; the leaves are 2 in. 

 long, in threes, their margins serrated and their ventral surfaces cemented 

 together in this specimen, so that the fascicles appear to be monophyllous ; 

 basal sheaths persistent ; the cones are borne on very long, stout, curved 

 footstalks. The structure of the cone, the extraordinary persistency of 

 the basal sheath in a Pine of such affiliations, all combine to establish 

 P. Nelsoni as a new and very curious species. — G. S. S. 



Pitcairnia spathacea. By C, H. Wright (Bob Mag. t. 7966).— 

 Native of Argentina. Nat. ord. Bromeliacea ; tribe Pitcaimiece. A 

 stemless plant. Leaves patent or recurved, 16 inches long ; panicle 

 2 feet long ; sepals pale rose, petals dull blue. — G. H. 



Placoneis : A new Diatomaceous Genus. By C. Mereschowsky 

 (Beth. Bot. Cent. xv. pp. 1-30).— Proposes a new genus to embrace those 

 species of Navicula which have one and not two endochrome plates. 

 There are 14 text figures and 1 plate. The paper is interesting as giving 

 an excellent account of the complex foldings of endochrome and other 

 details in the softer parts of diatoms ; but it is doubtful whether Placoneis, 

 the new genus, will be accepted by other diatomists, as it would be quite 

 impossible to use the ordinary methods for distinguishing species if details 

 of this sort are to be considered. All the species of Placoneis, or rather 

 of those of Navicula which have this structure, and also of Staurophora, are 

 considered. — G. F. S.-E. 



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