21C> SUMMAEY OF CURRENT RESEARCHES RELATING TO 



Anatomical Researches on Sea-side Plants.* — H. Chermezon finds 

 that the littoral flora is composed chiefly of a xerophilous and a halo- 

 philous flora. The xerophilous characteristics consist mainly of epidermic 

 protection. The leaves and even the stalks of halophilous plants are more 

 or less fleshy, and epidermic protection is rare. Both floras exhibit a 

 radial habit and a somewhat dense mesophyll. Certain dune plants 

 present a slight fleshiness and certain salt-marsh plants epidermic pro- 

 tection. Xerophilous plants occur frequently on the rocky shores of the 

 Mediterranean ; the fleshiness of the halophiles varies with the degree 

 of saltness and is greatest in the salt marshes. The resemblance between 

 the two floras has caused Schimper to confuse them, but as a rule halo- 

 philes do not present xerophilous characteristics, which could hardly be 

 accounted for, especially in salt marshes ; on the other hand several salt- 

 marsh species possess hygrophilous peculiarities. The sole characteristic 

 of halophiles is, in fact, the fleshy form, caused either by the number of 

 layers or by the size of the cells ; the fact that fleshy plants are found 

 other than on sea-beaches simply proves that fleshiness may result from 

 other causes than the presence of salt. The fleshy habit appears to aid 

 the plant in resisting the action of sea-salt, but some plants found in 

 very salt districts (Frankema, Statice, etc.) are not fleshy ; therefore 

 ability to withstand saltness must be something entirely specific. As to 

 the action of salt in the distribution of species, it is clear that a certain 

 degree of saltness eliminates many plants ; several authors have thought 

 that the localization of various species on the sea-shore is due to the fact 

 that they found less competition there ; but a flora such as that of the 

 salt marshes can hardly be considered as refugees, seeking a field for 

 expansion ; some of its species are not dependent on salt, but so far the 

 majority of them may be included among the true halophiles. 



Transitory Tissues in Vascular Plants. | — Gr. Chauveaud gives an 

 account of these tissues, which fall under the two heads of Secretory and 

 Conducting ; the former confined to a few, the latter found in plants 

 generally. 



Transitory Secretory Tissue. — The Gymnosperms are especially con- 

 cerned, and of them the yew, in which typical secretory canals are absent. 

 The secretory tubes with which the present paper deals keep their secre- 

 tion products, instead of passing them into neighbouring canals. 



The distribution and development of these tissues in the seedling of 

 Taxus baccata is described at length. The case of young organs on adult 

 parts is then dealt with. The arrangement in the case of a rootlet is the 

 same as in the radicle. At the growing-point of a stem the hypodermal 

 secretory system found in the hypocotyl is absent, and the same dis- 

 tinction obtains between cotyledon and young leaf. For the rest, the 

 disposition of the transitory secretory tissue is substantially the same for 

 hypocotyl and young stem, and for cotyledon and developing leaf, re- 

 spectively — namely, in arcs abutting on the phloem. The secretory tubes 

 ultimately become septate, and in adult parts are, save in rare cases, 

 indistinguishable from ordinary parenchyma. They are thus essentially 

 transitory in structure and function. 



• Ann. Sci. Nat. ser. 9, xii. (1911) pp. 117-313 (figs.), 

 t Tom. cit., pp. 1-70. 



