ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 327 



which they find the following types : — Transformation of the leaves into 

 pitchers, formation of pitchers upon the leaves, and formation of super- 

 numerary leaflets by proliferation of the nerves. The pitcher-like leaf 

 results from a compression of the young leaf in the bud, resulting in a 

 peltate widening development at the petiole ; it does not arise from union 

 of the leaf-margins. As such leaves are met with in many different 

 types from various localities, the action of the environment as a cause of 

 the deformation may be eliminated, nor is there evidence of any para- 

 sitic action. The author also describes the occurrence of abnormal 

 vascular bundles in the pith of Saxifrages ; the pith bundles show 

 inverse orientation, wood external and bast internal, and seem to be 

 due to a lateral proliferation of the cambial cells. He also describes in 

 the neck of the pitchers, wood islands, of primary origin, which have 

 become separated from the cambium by normal parenchyma. 



Anatomical Investigations on Stem-galls* — C. Houard has studied 

 in a large number of plants the structure of the so-called " terminal " 

 galls, which are characterised by arrest in the growth in length of the 

 internodes at the end of the stem, an increased diameter of the affected 

 region, and the consequent crowding of the leaves. In a previous, 

 memoir the author has dealt with the " lateral " galls, those in which 

 growth in length of the internodes is not arrested. The following are 

 the general conclusions arrived at : — The parasite affects the growing 

 point of the stem, setting up an action which finds expression in the 

 hypertrophy and cellular hyperplasy of the surrounding tissues. In- 

 crease in length of the shoot is arrested or stopped ; the upper internodes 

 remain short, and show a corresponding increase in thickness, as well as 

 important anatomical modifications. Cortex and pith'are generally more 

 developed, while the numerous fibro-vascular bundles are scattered irregu- 

 larly and without regular orientation. There is also absence of periderm, 

 and poor formation of secondary tissues. Associated with the arrest in 

 growth of the internodes is a diminution in growth in length of the 

 leaves, which become broader, thicker, and covered with hairs. Their 

 internal structure is generally much modified, showing arrest in differ- 

 entiation of the tissues — diminution of chlorophyll-containing tissue, 

 stomata irregular and without order, more numerous hypertrophied 

 vascular bundles, with irregular primary wood and slight secondary 

 formation. As a result the gall assumes a tufted form, like an artichoke 

 or large bud ; the original symmetry of the shoot is preserved, as the 

 attack of the parasite is at the growing point. The phyllotaxy of the 

 shoot attacked remains normal. Owing to interruption of the terminal 

 growth, lateral branchlets become developed. After the departure of 

 the parasite, growth is sometimes resumed in the shoot affected, and the 

 internodes become elongated. 



Regeneration in Passion-Flower.f — Hans Winkler describes the 

 formation in Passiflora cccrulea of adventitious shoots on tendrils which 

 had been cut from the plant and kept moist in sand. After several 



* Ann. Sci. Nat., ser. 8, xx. (1904) pp. 219-385 (289 figs, in text). 

 t Ber. Deutsch. Bot. Geaell.,xxiii. (1905) pp. 45-8 (1 fig. in text). 



