4-'0 



c|uickly, and, when the new \egetative period Ijegins. the de\el()i)nienl of 

 the buds is retarded and often entirely prevented. \\ ith such actixity in 

 the parts above ground, the roots will rot if given too abundant water. 



Various methods have been proposed to overcome the injurious in- 

 fluence of the dry air in the room, such as to spray frequently or to cover 

 the plants at night with damp cheese cloth, etc. However, such methods 

 have not proved sufficiently satisfactory. I obtained best results by using 

 Wardian cases or by setting the plants over water. Recently flower tables 

 have l)een used in which the plant stands on a zinc box filled with water, 

 the to]) of which has been punctured full of holes. Through this, water 

 vapor constantly rises between plants placed above it. 



TTard Sef.ds in the Lkguminaceae. 



The hard-shelled condition of T.eguminaceae seeds, not only those of 

 the Papilionaceae, but also those of the Mimoscae and Caesalpiniaccae, can 

 be considered as a natural protection against micro-organisms at a time in 

 their development when they are most readily infested. All our wild grow- 

 ing Papilionaceae exhibit the same constructive principle and the hard- 

 seeded condition becomes dangerous only when it ])rcvents germination. 



This hard-shelled condition arises from the special thickening of the 

 palisade layer of the seed grain which, with its cuticle, forms the outer- 

 most covering of ^the seed shell. These columnar palisade cells, lying \ery 

 close to one another, show in cross-section strongly refractive cross lines 

 (lu/ht lines) of an especially dense substance. The cell content contains 

 those substances which cause the coloring of the seed shell and to which 

 great importance is ascribed as substances protective against parasite at- 

 tacks. Next to the palisade layer, described by Nobbe as the "hard layer," 

 lies, on the under side, a layer of so-called hour-glass cells, next which are 

 thin-walled cell layers wnth large intercellular spaces. These cells function 

 especially in the sw^elling of seed. Corresponding to the gluten layer in 

 grain seeds, we find in the majority of Leguminaceae seed, with the ex- 

 ception of the Phaseoleae, Vicieae and a few other \arieties, according to 

 Harz\ the endosperm in the form of a hard, horny matter, which becomes 

 slimy when placed in water. In the region of the scar, palisade cells and 

 round hour-glass cells usually appear in two rows. 



In this instance we follow Hiltner's experiments'-, which show that the 

 hard-seeded condition preventing the rapid swelling of the seeds, naturally 

 forms a protection against micro-organisms. Older lupine seeds, which 

 w^ere not absolutely hard-shelled but swell up only Avith difficulty, were 

 soaked in water. The seeds which swelled each day were laid separately 

 in the germinating box. This showed that those lupine seeds which swelled 

 most rapidly and hence were not hard-shelled, almost always rotted, while 



1 Landwirtschuftlielie Samenkimde. 



- Hiltner, I..., Die Keimung.sverhiiltni.sse der Legumiiiosensamen und . ihre 

 Beeinflus.sung' durch Organismenwirkung. Arbeiten d. Biolog. Abteil. f. I.and- u. 

 Forstwirtsch. am Kaiserl. Gesundheitsamte. Vol. Ill, Part 1. Berlin 1902. 



