112 SUMMARY OF CURRENT RESEARCHES RELATING TO 



from old roots. The central vascular portion of the disc penetrates to the 

 pericycle of the host, from which it absorbs nutriment, the penetration 

 being effected by the secretion of some corrosive substance. 



The large cavities in the scale-leaves contain glands of three kinds, 

 viz. (1) Stipitate glands springing from a single epidermal cell; the pedicel 

 usually one-celled, the head composed of four cells filled with dense 

 granular protoplasm ; this is the most common form. (2) Sessile glands 

 with a broadly elliptical basal cell; the head composed of four long 

 narrow cells containing granular protoplasm ; this form is also abundant. 

 (3) Glands with long slender jointed pedicel and small multicellular head, 

 a<^reeing in structure with the glands that cover the rachis and bracts, 

 but which are very rare in the cavities. The cavities of the leaves do 

 not contain air, but water with an acid reaction, due to a secretion from 

 the stipitate glands. The large sessile glands exercise an absorptive 

 function, certain inorganic and organic matters from the humus being in 

 all probability absorbed and assimilated by the plant. 



Further details are given of the nature of the tissues of which the scale- 

 leaves are composed, as shown by microchemical tests. 



In some instances the roots are covered by the mycelium of a fungus ; 

 but this is not sufficiently constant to regard the phenomenon as one of 

 symbiosis similar to that which occurs in Monotropa. 



RMzopod-like Digestive Organs in Carnivorous Plants.* — Herren 

 A. Kerner v. Marilaun and E. Wettstein v. Westersheim describe the 

 contrivances for the capture and digestion of insects in Lathrsea squamaria 

 and Bartsia alpina. On the back of the underground non-chlorophyllaceous 

 leaves of Lathrsea are cavities, the inner walls of which are clothed with 

 glandular organs of two kinds, stalked capitate hairs and sessile 2-4-celled 

 sterile elliptical organs, the latter in connection with the vascular-bundle 

 system of the leaf. The outer membrane of both organs is provided with 

 extremely regular perforations, from which, under certain circumstance?, 

 extremely fine protoplasmic threads project outwards. These threads come 

 into contact with the products of decomposition of the animals (infusoria, 

 mites, &c.) which perish in the cavities. No excretion of any special fluid 

 could be detected. At the commencement of the period of vegetation, 

 the absorption of nutriment in Lathrsea takes place chiefly through the 

 haustoria, and the quantity of the remains of animals found in the cavities 

 is extremely small. Towards autumn the haustoria partially disappear, 

 and the number of insects captured increases. 



In Bartsia alpina similar organs are found in peculiar hollows formed by 

 the leaves, the margins of which are recurved in vernation. The leaf-buds are 

 underground, and the structure of the cavities is similar to that in Lathrsea. 



Forms of Leaves and Cotyledons. f — The presidential address of Sir 

 John Lubbock to the Linnean Society is devoted to a discussion of the 

 forms of the leaves and cotyledons of Flowering Plants in relation to 

 their biological requirements. After a few remarks on leaves, especially 

 in regard to their form and their venation, he proceeds to a discussion 

 of seedlings. The variations in the cotyledons of dicotyledonous plants 

 are described, especially in relation to their size and form, the likeness or 

 unlikcness of the two cotyledons to one another, and the size of the embryo 

 in comparison to that of the seed. Sir John Lubbock concludes that the 

 conditions under which seedlings are grown naturally exert some influence 



* SB. K. Akad. Wiss. Wien, xciii. (188G) (1 pi.). Slg Cot. Centralbl., xxvii. (1886) 

 p. 289. 



t Journ. Linn. Soc. Lond. (Bot.), xxxii. (188G) pp. 341-iOl (134 figs.). 



