NOTES AND ABSTRACTS. 



775 



in Abies Pinsapo in his present paper, but he has already described it in 

 other Con if era elsewhere. A section through the radicle in one stage 

 shows : (a) a thick external part of the phloem, the " liber precurseur " ; 

 (b) a thinner middle layer, the primary phloem ; (c) a very thin inner 

 part, the beginning of the secondary phloem ; in addition there are 

 secretory canals of the pericycle region. The "liber precurseur " is made 

 up of elongated elements with sieve-plates, generally unthickened, but in 

 A. Pinsapo thickened so as to be indistinguishable from adjoining primary 

 phloem sieve-tubes. This tissue is confined to radicle, hypocotyl, and 

 cotyledons (the figures show its occurrence in each of these), and it is not 

 found in the later-formed stem and leaves. — W. G. S. 



Conifers, Centripetal Wood in Leaves of. By Dr. Ch. Bernard. 

 (Beih. Bot. Cent. xvii. pp. 241-310 ; with 88 figures and 1 coloured plate). — 

 Describes and figures the anatomical structure of the leaves of a great 

 number of the rarer species of Conifer 'ce and of Cycads. His conclusions 

 are that transfusion tissue is notning but the centripetal wood to be 

 found in all stages of transition from Cycad to Pinus. Its function may 

 be changed ; it can be adapted to the conduction of sap (" sues "), and thus 

 its origin may be rendered obscure ; but the mesarch nature of the bundles 

 will be evident in these individuals which retain their ancestral characters. 

 The Conifers are " diploxylons," but the reduction of the centripetal 

 wood is accentuated. The "parenchyme transversal" or "accessory 

 transfusion tissue " is morphologically separate, though it may be 

 physiologically a continuation of the centripetal wood. It has most 

 frequently a supporting function. The author calls this tissue " hydro- 

 stereome transversal." The most important character of centripetal wood 

 consists in the presence of small elements situated against the protoxylein. 

 After these, follow two lateral wings which lead to lignified cells, which 

 are larger, pitted, spirally, or reticulately thickened. This character is 

 sometimes so evident that, in the less modified types, the circular arc 

 which is typical of Cycads may be found. It is probable that, in the more 

 modified types, the origin of the centripetal wood may be found by taking 

 series of sections, or by studying cotyledons, very young ieaves or, perhaps, 

 cone-scales. There is a bibliography of 58 numbers, and the plate and 

 figures are extremely well done. — G. F. S.-E. 



Conifer Disease, A. (Botryk ea, Pers.) (Jour. Bd. Agr. vol. x., 



No. 1, pp. 17-21, with coloured plate ; 1903). — This disease was first dis- 

 covered in Germany attacking the topmost shoots of seedlings, also the 

 tips of the lower branches of older trees. This fungus causes the shoots to 

 " curve downwards or become variously twisted, and tbe leaves die and 

 become separated from the branches, but are frequently prevented from 

 falling, being held in a tuft by a delicate weft of brown, cobweb-like 

 mycelium." The young shoots of Silver Fir (Abies pectinata DC), Spruce 

 (Picea excelsa Link), and Larch (Larix europaa DC.) have been success- 

 fully inoculated with this disease. It has also been observed on Junipers, 

 and in Hungary on species of Abies, Picea, and Larix ; in the British Isles 

 on Pinus sylvestris L., and seedling Wellingtonias. 



Preventive Measures. — "Perfect cleanliness in the seed-beds is of primary 



