ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 659 



of Liliaceae, all perennial herbs. In species of Clintonia, Prosartes, and 

 Fritillaria the rhizome alone by its movement of growth determines 

 the position of the plant. It grows horizontally and is influenced as 

 to its position by the roots which are not contractile. In species of 

 IAlium, Scoliopus, and Trillium, on the other band, the roots are con- 

 tractile and mainly determine the position of the horizontally develop- 

 ing rhizome. In Zygadenus, Chlorogalum, Calochortus, and Brodisea the 

 rhizome develops vertically and the contractile roots determine almost 

 exclusively the position of the plant. In the first seven genera men- 

 tioned the roots are of the same kind, but in the last three there is a 

 morphological and physiological differentiation of labour into nutritive 

 and contractile roots. The age of the roots amounts to years in Clintonia, 

 Prosartes, Scoliopus, and Trillium, but to a few months only in Fritillaria, 

 Zygadenus, Chlorogalum, Calochortus, and Brodisea. Contractility occurs 

 not only in long-lived roots but also, and in a very high degree, in 

 short-lived ones. Long-lived roots assume also the function of storing 

 reserve material, they may be contractile as in Scoliopus and Trillium, 

 or not contractile as in Prosartes and Clintonia. 



Rejuvenescence as a Result of Grafting.* — L. Daniel describes 

 the result of grafting an herbaceous annual Scopolia carniolica on a 

 young tomato plant. Scopolia carniolica is one of the earliest spring 

 flowering plants. On May 1st, its aerial shoots, which were beginning 

 to dry up and perish, were grafted on a young tomato which at that 

 time was at the beginning of its development and growing actively. 

 The graft succeeded, and renewed its growth, producing in succession 

 buds and leafy branches, and in one case an inflorescence and fruit. 

 The plants are both members of the same order, Solanacese, but belong 

 to different tribes, viz. Hyoscyameae and Solaneae respectively. The 

 experiment shows that likeness of habit between stock and graft is not 

 essential to success, and also the possibility of a rejuvenescence of shoots 

 which are already in a state of senility. The operation has moreover 

 profoundly modified the habit of the graft, so that a second flowering 

 has occurred. 



Structure of the Wood in Deciduous and Evergreen Trees.f — 

 S. Simon formulates the following results of his investigations in the 

 distribution of tissue in woody plants of the temperate zone. In the 

 case of nearly allied plants growing under the same climatic conditions, 

 the one deciduous and the other evergreen, there is a greater tendency 

 in the former, owing to its more limited period of assimilation, to 

 develop storage tissue. This tendency is checked only when the de- 

 ciduous plant has some compensating contrivance which acts as a com- 

 plete or partial equivalent for the evergreen leaf. Corresponding to 

 the' less extent of storage tissue is a greater development of mechanical 

 tissue in the evergreen plant. This is correlated with the general 

 xerophytic character of these plants, which for the same reason have 

 less conducting tissue. As regards distribution of tissue, the conduct- 

 ing elements occur fairly evenly throughout the annual ring in ever- 

 green trees, corresponding with the more even distribution of activity 



* Comptes Kendus, exxxv. (1902) pp. 481-2. 



t Ber. Deutsch. Bot. Ges., xx. (1902) pp. 229-49 (1 pi. and 3 figs.). 



2 y 2 



