554 
SUMMARY OP CURRENT RESEARCHES RELATING TO 
and deduces from them some general laws, comparing these with the 
conclusions of previous observers, witli which they do not always agree*. 
He contests the theory that each specific abnormality in structure is the 
result of some specific abnormality in the external conditions, referring 
them rather to internal causes. 
Hydathodes. — Herr 0. Spaujer * gives a resume of the present state 
of our knowledge with respect to the exudation of water from leaves, 
with a list of the orders and species of Phanerogams and Pteridophyta 
in which it has at present been observed. With regard to the function 
of the secreting organs, he considers that it cannot he primarily the 
exudation of water, since even in those plauts in which it is most active 
(the Rosaceae), the amount of water given off is trifling compared to that 
eliminated by transpiration. It is probably rather the promotion of the 
transport of mineral and other food-materials through the plant. The 
different forms of structure are arranged under several types, each in 
most cases belonging to a number of nearly allied genera. The appa- 
ratus for the exudation of water is described by the author as consisting 
of the following elements : — the termiuations of the vascular bundles ; 
the epithelial sheath ; the epithele ; the aquiferous chamber ; the fissure. 
Some of the controversial points in this paper are vigorously com- 
bated by Herr G. Haberlandt, f who charges Spanjer with misrepresent- 
ing his statements on some points; with ignoring well-known observa- 
tions of competent authorities ; and with bringing forward no new facts 
in support of his theories. In particular he contests Spanjer’s assertion 
that there is no active secretion of water through hydathodes of a glan- 
dular nature. These have been observed by Haberlandt in Phaseohis 
multiflorus and Anamirta Cocculus ; by Goebel and Groom in Lathrsea 
and other Rhinanthese ; as well as by Treub and Koorders. 
Herr A. Meyer J defends the conclusions arrived at by Spanjer against 
the attacks of Haberlandt. 
Size of the Leaves of Conifers.§ — According to observations made 
by Mr. E. P. Copeland on American conifers, the variation in the size 
of leaves of the same season is a rhythmic one. and displays great regu- 
larity. Those formed at first are very short ; they are afterwards longer ; 
and at the end of the season again short, generally shorter than the 
earliest. This is attributed by the author either to the direct or to the 
hereditary influence of the variations in the vital activity at different 
periods of the year, as the plant gradually arouses from its winter rest 
in spring and sinks again into it in late summer and autumn. 
Double Root- cap of Tropaeolum.|| — M. C. Brunotte has investigated 
the structure of the double root-cap of Tropseolum, and states that the 
supernumerary sheath originates from the proliferation of the cells of 
the suspensor. 
Structure of Myristicaceae.1T — Herr 0. Warburg publishes a detailed 
monograph of this order, preceded by a description of the anatomical 
' * Bot. Ztg., lvi. (1898) l le Abt., pp. 35-81 (1 pi.). Cf. this Journal, ante , p. 95. 
t Op. cit., lvi. (1898) 2 te Abt., pp. 178-81. + Tom. cit., pp. 241-5. 
§ Bot. Gazette, xxv. (1898) pp. 427-36. 
|| Comptes Rendus, exxvi. (1898) pp. 277-9. 
Nova Acta Acad. Cses. Leop.-Oarol., Ixviii. (1897) pp. 1-680 (25 pis.). 
