NOTES ON EECENT RESEARCH. 



515 



The growth in thickness of the middle lamella can often he traced- 

 It consists, therefore, of the layers first deposited by the plasma mem- 

 branes, plus a certain amount of material subsequently deposited in 

 contact with these layers, which is generally rich in pectic compounds as 

 compared with the still later deposited strata. 



As the cells grow to maturity the middle lamella loses its power of 

 adapting itself to the varying forms of the adjoining cells, and becomes 

 fixed and inflexible. This is due to the pectic acid changing into 

 insoluble pectates, chiefly the calcium salt. In cork cells of Tilia it 

 becomes changed to suberin. 



Such appears to be, in brief, its history from its commencement in a 

 dividing cell to the permanent and lifeless condition, as of cork, bast, and 

 wood. — G. H. 



Leaves. 



Leaves, on the biolog'ical types of, belonging* to the orders 

 Fag'acese, Monimiaceae, Melastomacese, Euphorbiace8e,Piperaeeae^ 



and Chloranthaceae. By Prof. Dr. Anton Hansgirg (Prague) (BeiJi. 

 Bot. Cent. bd. x. ht. 7, pp. 458-480). — The chief types in the genus 

 Qucrcus may be placed as follows : — 



I. Deciduous Leaves. — Glabrous or slightly hairy, sometimes felted on 

 underside. 



II. Leaves Evergreen. — Dry-climate oaks with leaves more or less 

 leathery, glabrous or thickly hairy below, entire or spinose at margins. 



All the species are enumerated and placed in position. Besides these 

 two main classes, the following are mentioned : — 



1. Poplar-like wind-leaf, Q. petiolaris &c. 



2. Kain-leaves with acuminate apex (Driptip), Q. cuspidata &c. 



3. Arranged to allow light to pass to lower leaves {Q. Bohur form). 



4. Ericoid rolled leaves, Q. vulcanica &c. 



5. Leaves with wax outgrowths Q. rig Ida. 



6. Leaves with many small glands, Q. resinosa &c. 



7. Glandular toothed leaves of Q. glandulifera &c. 



8. Spinose toothed leaves armed against animals, Q. acutifolia kc. 



9. Gnaphalium-like leaves, Q. Helferiana &c. 



10. Leaves with a more or less developed amount of tannin, 

 raphides, kc. 



Dimorphic leaves also occur. 



The genus Fagus and the other natural orders mentioned above are 

 treated in a similar manner, the leaves of all the species being classified 

 according to their functions. The classification follows that in the 

 author's " Zur Biologie der Laubbliitter," 1900.— G.F. S.-E. 



Locust Fungus. 



Locust Fungus. By G. Lindau {Not. Konig. Bot. Brrlin, No. 26, 

 b. iii. p. 109, July 5, 1901, 1 tab.) — For some time it ha^ been known 

 that the locusts of South Africa suii'er from the attacks of a parasitic 

 fungus, and it is but a short time ago that we heard of cultures of the 

 infective material being successfully distributed in order to encourage 



