ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 989 



tlio pigment wliicli are of the least importance in assimilation. A number 

 of tables of wavc-lengtbs and curves complete tbo paper. 



Yellow Spots on Leaves.* — Dr. P. Sorauer bas investigated tbe cause 

 of tbe yellow spots on tbe leaves of a number of plants, and finds it due 

 in all cases to a strctcbing of tbe cells of tbe mesopbyll. Tbe cells ai-e at 

 first emjity, but become afterwards filled witb a brown substance resulting 

 from tbe breaking up and disintegration of tbe cblorophyll-grains in adjacent 

 cells. 



Bud-scales.f — Herr E. Cadura classifies the coverings of tbe buds of 

 exogenous trees under four types, viz. (1) Collencbymatous coverings, 

 consisting of elongated collencbymatously tbickened parencbyma ; (2) 

 Parencbymatous covfirings ; (3) Periderm-like coverings, witb parencby- 

 matous cone and suberized apex ; (4) Stereid-like coverings, witb specific 

 mecbanical tissue. In tbe seventeen species examined, be finds one or 

 otber of tbese modes present, according to tbe need of tbe species for 

 l)rotection against excessive evaporation, radiation, cold, &c. 



Tbe casting-ofi" of tbe bud- scale is brougbt about by tbe formation of a 

 zone of tissue at tbeir base, the pheUoid, tbe cells of wbicb contain large 

 quantities of starcb and granular protoplasm, and in wbicb intercalary 

 growtb takes place owing to tbe traction exercised by tbe swelling bud. 



Gentians. :j:— Prof. T. H. Huxley gives the results of a survey of tbe 

 natural order Gentianacefc. Confining himself almost entirely to tbe study of 

 tbe structure of the flower, be w'as able to distingush some seven or eight 

 modifications ; and these were found to fall into two series, characterized by 

 a peculiar disposition of the mechanical organs. The corolla presents a 

 gradation of forms from the rotate, or rather stellate, condition, through tbe 

 campanulate, to the extreme infuudibuliform character. In one of tbese 

 series the nectarial cells are situated on the inner siirface of the cup, from 

 the edge of which tbe lobes of the corolla proceed, and towards its basal end. 

 The Gentianacefe of this series the author terms Perimelitse. In tbe other 

 series there are no such patches of secreting cells visible on the corolla ; 

 but in many members of the series there is a zone of such cells, encircling 

 the base of tbe ovary. These are termed Mesomelilse. 



In the series of the Perimelitse four modifications of floral structure 

 are discernible, and about the same number in the Mesomelitse. Tbe 

 author gives names to each of these groups, and traces their relationship 

 one to another, and also the geographical distribution of each. 



Inflorescence of Typha.§ — From a comparison of the structure of the 

 inflorescence in the few species of Tijpha, Dr. M. Kronfeld supports 

 Celakovsky's view that it is essentially of the same type of structure as that 

 of Sparganium, and that the distinct zones of flowers are in reality axillary 

 shoots. Even the female partial inflorescence is composed of several, or at 

 least of two, internodes. 



Axis of the Inflorescence, (j — Dr. E. Dennert discusses in great detail 

 tbe variations in tbe anatomical structure of this organ, to adapt it to 

 different conditions. At tbe time of flowering the passage from the leafy 



* Forsch. a. d. Geb. d. Afrriculturphysik, ix. pp. 387-9G. See Bot. Centralbl., xxxi. 

 (1887) p. 279. 



t Cadura, R., ' Physiol. Anat. d. Knnspcn-decken dikotyler Laubbilumc' 42 pp., 

 Bi-cslau, 1887. See Bot. Centrall)].. xxxi. (1887) p. 87. 



X Journ. Linn. Soe. Lond. — Bot., xsiv. (1887) pp. 101-24 (1 pi.). 



§ SB. K. Akad. Wiss. Wien, xciv. (1887) pp. 78-108 (1 pi. and 2 figs.). Cf. this 

 Journal, ante, p. 114. 



II Wigand's Bot. Heftc, ii. (1887) pp. 128-217 (1 pi.). 

 1887. 3 T 



