ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 471 



BOTANY. 



GENERAL, 



Including the Anatomy and Physiology of Seed Plants. 



Structure and Development. 

 Vegetative. 



Aerial Roots of Tibouchina Moricandiana.*— B. Chandler has studied 

 the aerial roots of T. Moricandiana. These roots usually arise from the 

 nodes of the upper branches, and are from 10-15 cm. long ; they are 

 mostly negatively geotropic. They are short-lived, and have no great 

 functional activity. When cut off and grown in soil the roots lengthened 

 but did not branch, but if forced under the soil while still in connection 

 with the stem, they gave off lateral roots and behaved like ordinary 

 aerial roots under similar conditions. The root-tip of these aerial roots 

 dies rapidly and the tissues arouud continue to grow until a swelling 

 like a callus-cushion surrounds the dead tip. From this callus a circlet 

 of roots may grow out, or the swelling may form a bilobed root or even 

 a fasciated structure. The most curious phenomenon exhibited by these 

 roots is the manner in which an inner cambium derived from the pith 

 completes the severed portions of the vascular system found in each 

 lobe of the root. Xylem and phloem are developed in normal sequence 

 but in inverted position in respect to the pith cambium. 



Parasitism of Lathrsea clandestina.f — M. Col contributes a note 

 upon L. dandestina, which has lately appeared as a parasite upon the 

 vines in the lower Loire district. The root-suckers differ from those of 

 L. Squamaria in being of larger diameter and fewer number ; they do 

 not ramify, but are of the " compact sucker " type. The new host does 

 not appear to have modified the structure of the parasite. It is also 

 strange to find that this plant, which is usually regarded as characteristic 

 of humid districts, has invaded a soil which is dry and has a stony subsoil. 



Physiology. 

 Nutrition and Growth. 



Green Plants and Carbon Monoxide. $ — Th. Krascheninnikoff has 

 made a number of experiments upon green plants, in order to discover 

 whether a green plant exposed to light can obtain its carbon directly 

 from this gas. The experiments have been made under the most 

 varied conditions, but they all tend to show that no absorption takes 

 place. Further, the presence of CO has no effect upon the decomposi- 

 tion of CO.,. In spite of these negative results the author does not 



* Notes Roy. Bot. Gard. Edinburgh, xx. (1900) pp. 247-250 (1 pi.), 

 t Comptes Rendus, cxlviii. (1909) pp. 1475-70. 

 % Rev. Gen. Bot., xxi. (1909) pp. 177-93 (1 pi.) 



