3] Lehr- und Handbücher. Zusammenfassende Darstellungen 259 



IG. Kohlschütter, V. D i e E r s c heinungsf o r m e n d er Materi e. 

 Vorlesunge n über K o 1 1 o i d c h e m i e. (Leipzig, B. G. Teubner, 1917. 

 X u. 35ö pp.) — Ref. in Bot. Ctrbl. 141. 1919, p. 82—83. 



17. Lepeschkin, N. W. V o riesungen über Physiologie der 



Plauzen. (Kasan 1918, VI u. 632 pp.) — Ref. in Bot. Ctrbl. X. F. 2. 1923, 

 p. 198. 



18. Lob, W, E i n f ü h run g in die Bioche m i e. (Aus Natur und 

 Geisteswelt Nr. 352, 2. Aufl. [Leipzig, B. G. Teubner, 1918], 82 pp. mir 

 12 Textfiguren.) — Behandelt den Stoff kurz vom botanischen und zoologi- 

 schen Standpunkte. F e d d e. 



19. Lundegärdh, H. Vax t er na pä krigsstigen och i f re ti- 

 li ga v ä r o. [Die Pflanzen als Krieger und in friedlichem Geschäft.] (8°, 

 144 pp., 89 Abb. [Stockholm, Albert Bonnier, 1917].) — Eine Sammlung all- 

 gemeinverständlicher Aufsätze und Plaudereien pflanzenphysiologischen In- 

 halts. Viele instruktive Abbildungen nach photographischen Originalauf- 

 nahmen des Verfs. Collande r. 



20. Lundegärdh, H. V a d m ä n n i s k a n tankt o m 1 i v e t. [Was 

 der Mensch vom Leben gedacht hat.] (8°, 164 pp., 47 Abb. [Stockholm, Hugo 

 Geber, 1917].) — Populäre naturwissenschaftliche Essays. 



Collande r. 



21. MacDougal, I). T.. Richards, H. M. and Spoehr, H. A. Basics of 

 succulence in pla nts. (Bot. Gaz. 67, 1919, p. 405—416.) — Die Be- 

 obachtungen und Versuche werden wie folgt kurz susammengefal.st: 

 1. A Castilleja native to the region about the Coastal Laboratory, at 

 C a r m e 1 , California, includes two habitats forms, genetically identical, 

 one with t hin leaves growing in the open forest formation, and another wilh 

 fleshly leaves growing on the sandy foreshores under arid, but not saline, 

 soil conditions. 2. The thin leaves show an acidity double that of the fleshly 

 type, and have a relatively greater dry weight. 3. The fleshly leaves, fresh 

 and in a dried condition, present swelling reactions similar to these sections 

 of the joints of platyopuntias, indicative of cells high in pentosans, 

 or mucilages. The behavior of these organs is different in many importaut 

 particulars from that of thin leaves, which swell more in acid than in alkaline 

 Solutions, the reverse taking place in succulent leaves, in parallelism to 

 Opuntia. 4. Differences in the swelling reactions of dried leaves of both kinds 

 are to be described to the adsorption of the contained acids and salts of 

 different amounts in the two cases on cell colloids, bigh in pentosans in one 

 case and hence presenting characteristic coagulating effects. 5. It has been 

 established by researches not described in this paper that the reduction of 

 the water content of the cell ;below a certain point results in the conversion 

 of Polysaccharides, which do not show a high Imbibition capacity, to pentosans, 

 which mixed with nitrogenous substances have an enormous hydration capa- 

 city. 6. Succulence, therefore, may originale as it is seen to occur in 

 Castilleja as a direct result of aridity. Species of Ericctmeria and Erigeron 

 with a distribution similiar to Castilleja display thin and succulent leaves 

 corresponding in the same manner to the environment. 7. High acidity may 

 not be taken as a result of succulence. It is probably more nearly correct to 

 assume that succulence may develop only in plants which have a carbohydratc 

 metabolism characterized by large acid residues. 



17* 



