37 



We can dispose briefly of the cell inclusions which, ±\. 

 additions to the chromatophores, come under our consideration. 

 Particularly important are the crystals of calcium oxalate, 

 the formation and distribution of which is, to a high de- 

 gree, dependent on external factors, a. F. W. Schimper, 

 Kohl, Wehner, and others-^ have already furnished contri- 

 butions to the knov;ledge of the conditions under which 

 the normal formation of the crystals takes place. Their 

 results, however, are not without contradictions and a thor- 

 ough comprehensible treatment of the question is still want- 

 ing*. It may only be said with certainty that lowered trans- 

 piration decreases the number of crystals; shade leaves con- 

 tain fewer crystals than do sun leaves and specimens culti- 

 vated in moist air, or without light, are also poor in 

 crystals, as likewise are parts .of variegated leaves free 

 from chlorophyll. According to Rauwenhof f^ , etiolated spec- 

 imens of Polygonum cuspidatum entirely lack crystalls. More 

 investigations of this would be desirable. Vandevelde^ proved 

 further , that leaves bearing galls are especially poor 

 in crystals. Future investigators v/ill have to notice 

 whether abnormal life conditions can also influence the form 

 of the individual crystals and possib^-y prevent the develop- 



1. Schimper, A. P. V/, Ueber Kalkoxalatbildung in den 

 Blattern, Bot. Zeitg, , 1888, Bd. XLVI , p, 65. Kohl, Anat,-phys, 

 Untersuchungen der Zalksalze und Riesselsalze in der Pflt, 

 Marburg, 1:889, p. 50, and elsewhere. Wehraer, Die Oxalatab- 

 scheidung im Verlauf der Sprossentwicklung u. s. w. Bot, Zei|g. 



1891, Bd» XLIX, p. 149. Zur Frage nach dem Fehlem oxals, 

 Salae. Landwirtsch. Versuchsstat, , 1892, Bd, XL, p. 109. 

 Among other literature may be mentioned, Monteverde, Uber den 

 Einfluss des Lichtes auf die Bildung des oxals. Kalkes in der 

 Pfl, (Russiah) . Arb, Petersb. Uaturf. Ges. Bd, XVIII, p. 46. 

 Cuboni, App s. anat. e fisiol. d. foglie d. vite, Riv, Enol, 

 e Viticolt,, Serie II, Vol. II (compare Bot. Cbl. , 1884, 

 Bd, XVII, p. 332). Dufour, Infl. de la lumiere s. la forme et 

 la struct, d. feuilles. Ann. Sc. Hat. Bot. VII, serie, T. V. 

 1889, p. 311. Buscalomni. Studii sui cristalli di ossalato 

 di calcio, Malpighia, 1896, Vol. IX, p. 469. 



2, S, 1, causes et 1, formes anormales d, pi, qui, orois- 

 sent d. I'obscurite. Ann. Sc. Nat. Bot., VI. Serie, T. V. 

 1877, p. 267, 



3. Bijdr. tot de phys, d. gallen; het aschgehalte d. an- 

 getocte bladern, Bot. Jaarb. Dodonea, 1896, Bd. VIII, p. 102. 



