500 SUMMARY OF CURRENT RESEARCHES RELATING TO 
orchid of Singapore) growing partly in the sun and partly in the shade, 
strong sunlight and drought combined have the effect of causing a 
distinct elongation of all the cells in the exposed leaves in a direction 
at right-angles to the surface ; the cuticle is better developed, and the 
leaf as a whole is thicker and smaller. 
Leaves of Iridese. — Mdme. Balicka-Iwanowska * has studied in 
detail the anatomical structure of the leaves of Iris and allied genera 
from a systematic point of view. She states that characters derived 
from this organ must be treated in connection with others dependent on 
the morphology of the flowers. In some cases, however, histological 
characters may be used in defining genera or groups of genera. Thus 
Patersonia is characterized by marginal emergencies and by a lignified 
pith ; Crocus and Bomulea by the section of their leaves ; Gladiolus by 
a completely lignified fibrovascular bundle in direct contact with the 
epiderm ; Iris and allied genera by their marginal hypodermal fibres. 
The genus Iris may be divided into three sections according as the 
leaves are tetragonal, equitant, or isolateral. The Ixieee and GladiolesB 
have isolateral leaves with a prominent mid-rib which is wanting in 
the IridinesB and Aristess. The Cipurinem and Tigridieae have 
folded leaves. Tritonia and allied genera have marginal epidermal 
fibres, and opposite or even coalescent bundles. With the exception 
of Iris , Morsea, Galaxia , and Crocus , all the Iridese have isolateral 
leaves. 
Dr. H. Ross f gives a detailed account of the comparative anatomy 
of the leaves of Iridese, derived from a study of 53 out of the 57 genera, 
and 300 out of the total number of about 700 known species. After a 
description of the general conformation of the leaves, special attention 
is directed to the epiderm and trichomes, the fibrovascular bundles, and 
the mesophyll. The specialities of the genera Iris , Hermodactylus, and 
Morsea are then referred to. 
Structure of Lathrsea.J — Herr E. Heinricher has paid special atten- 
tion to the structure of the underground organs and the mode of 
parasitism of Lathrsea squamaria and L. clandestina. The former was 
found parasitic only on Alnus incana. The haustoria occur, as a rule, 
not on the primary, but only on the lateral roots ; they are not placed, 
as has been described, exclusively at the extremity of the root-branches ; 
they are found along the whole length, and frequently give them a 
moniliform appearance. The author finds no confirmation of the state- 
ment of Kerner that the haustoria disappear completely in the autumn, 
and that the parasite connects itself again with its host in the spring by 
fresh haustoria. L. clandestina differs from L. squamaria chiefly in the 
abundant formation of roots on the rhizome. 
The succulent capsule of Lathrsea is forced open, when ripe, by the 
excessive development of the placenta. L. squamaria forms a large 
number of underground cleistogamous flowers which pass by insensible 
gradations into the ordinary open flowers. 
* Arch. Sci. Phys. et Nat., xxviii. (1892) pp. 413-35 ; xxix. (1893) pp. 185-200, 
225-41 (3 pis. and 15 figs.). Cf. this Journal, 1892, p. 818. 
f Malpighia, vi. (1892) pp. 90-116, 179-205 (4 pis.). 
X Ber. Deutsch. Bot. Gesell., xi. (1893) pp. 1-18. Cf. this Journal, ante , p. 63. 
