410 SUMMARY OF CURRENT RESEARCHES RELATING TO 



{Sedum album, Berberis cretica) or from both sides {Aristolochia 

 rotunda). 



2. Subfoliar. Either a single one from the point of insertion of 

 the leaf (Muhlenheckia complexa), or several in a whorl (Houttuynia 

 cor data). 



3. Suhstipular. From the lower surface of the stipule (Modiola 

 caroliniana). 



4. Axillo-foliar. From the axils either of aerial leaves {Grassula 

 perfossd) or of underground scale-leaves (Mahonia Aquifolium). 



5. Axillo-stipular. From the axil of stipules ( TJrtica dioica). 



6. Latero-gemmar. In connection with the axillary bud, either 

 on one side (Galystegia sepium) or on both sides [Spircea sorhifolia) ; 

 sometimes only from one of two opposite buds (Paronychia capitata). 



7. Supragemmar. From immediately above the axillary bud 

 (Lythrum Salicaria, Lysimachia verticillata). 



8. Suhgemmar. From below each bud (Equisetacese, Meni- 

 spermum canadense). 



Penetration of Branches of the Blackberry into the Soil.* — J. 



Wiesner finds that the winter-buds of species of Buhus growing in 

 woods with creeping branches are drawn into the soil by the shorten- 

 ing of the roots which spring from the apex of the shoot. This 

 shortening takes place in the roots of the zone above the growing 

 region, and results from increase of turgidity, in consequence of which 

 the growing part of the root lengthens. On the boundary of these 

 two zones of the root which behave in opposite ways are the root- 

 hairs, which fix the root firmly into the ground by becoming closely 

 attached to particles of soil. In consequence of this, the upper zone 

 of the stem becomes shorter, and the apex and growing region of the 

 root cannot be drawn out or injured. The traction on this lower part 

 resulting from the shortening of the upper part, is, however, weakened 

 by the fact that, under the conditions in which the upper apex of the 

 root becomes shorter, the lower or growing region stretches. The 

 traction caused by the shortening is exerted simply in dragging the 

 apex of the root into the soil. The shoots which root at their apex 

 become also thicker at their upper end, which could only result from 

 a reversal of the stream of water and from a movement of the 

 protoplasm in a direction opposite to the normal one. 



Circumnutation and Twining of Stems.f — J- Baranetzki argues 

 in favour of Schwendener's view that the twining of stems is due to 

 circumnutation and geotropism, rejecting de Vries's theory of the 

 influence of the weight of the terminal bud. 



Vegetable Acids and their eiFect in producing Turgidity. J — 

 According to H. de Vries, organic acids are never absent from the 

 growing parts of plants ; they are the principal, and frequently the 

 only causes of turgidity. They are not usually free, but most commonly 



* SB. K. Akad. Wiss. Wien, Ixxxvii. (1883) pp. 7-17. 



t Mem. Acad. Imp. Sci. St. Petersbourg, xxxi. See Bot. Ztg., xli. (1883) 

 p. 855. 



X Bot. Ztg., xli. (1883) pp. 849-54. 



