Retinia Austriana, n. sp.—The Austrian Pine (Pinus laricio Austriaca) in the vicinity of Toronto is badly infested by the larveæ of a moth which is apparently an undescribed species of the genus Retinia. It resembles in certain particlars the form Retinia Comstockiana. This species was described in the Canadian Entomologist of Aug., 1879, by Prof. C. H. Fernald State College, Orono, Me. The specimens, however, were obtained at Ithaca, N.Y. Where they were found boring in the small branches of Pinus rigida.
During a study on the live crown characteristics of Pinus laricio (Pinus nigra Arn. ssp. laricio (Poir.) Maire), the observation of branch cross-sections allowed us to work on the problem of the discontinuance of cambial activity. This work points out the existence of missing rings with a histologic point of view and establishes the generality of the phenomenon for this species. In addition to the observations at the base of living branches, the cross-sections in all the successive growth units of the branch were observed to establish the distribution of the annual wood layers along the branch and to ascertain the dissymmetry between the upper side and the lower side of the branch. The occurrence of this phenomenon in the upper part of the crown raises the problem of the contribution of these branches to tree development and its implication in forest management.Key words: growth rings, Pinus nigra Arn. ssp. laricio (Poir.) Maire, missing rings, anatomy, branch growth, crown.
Untersuchungen über die Sekrete. Ueber den Harzbalsam von Pinus Laricio Poiret (Oesterreichischer Terpentin)
