56 The Pi^ant WorIvD. 



Gager produced chromosomic irregularities by the exposure 

 of ovaries of Oenothera to radium emanations a few years ago, 

 and some of the progeny from treated parents were aberrant, 

 although the transmissibility of the new characters was not 

 tested. 



Klebs, who has long been concerned with the morphogenic 

 reactions of plants, has determined a series of conditions under 

 which the stages of mycelial development, asexual, zoospore, 

 and sexual or oospore formations in filamentous fungi may be 

 inhibited or variously interchanged. Much mare important 

 reactions were obtained from Sempervivum, the Live-Forever 

 of the garden. In this plant dense rosettes or propagative 

 bodies are formed at the ends of some branches, and inflorescences 

 were replaced by single flowers by experimental excitation; the 

 number and arrangement of the floral organs as well as of the 

 stamens and carpels could be altered. Furthermore, the devia- 

 tions in question were found to be transmissible in guarded seed- 

 reproductions. 



The fortunate experience of Zederbauer with Capsella has 

 yielded some conclusions of exceptional importance. A genotype 

 of Capsella Bursa-pastoris resembling C. taraxicafolium was 

 found on the lower plains of Asia Minor, and displayed the well- 

 known characters of this form, including broad leaves, whitish 

 flowers, and stems 30-40 cm. high. A highway leads from these 

 regions to a plateau at an elevation of 2,000 to 2,400 meters. 

 The conditions of distribution are such as to indicate that the 

 plant has been carried up this thoroughfare by man, and in this 

 elevated habitat it has taken on certain alpine characters, in- 

 cluding elongated roots, xerophytic leaves, stems 2-5 cm. high, and 

 reddish flowers, with a noticeable increase of the hairness of 

 the entire plant. That the distributional history has been cor- 

 rectly apprehended seems entirely confirmed by the fact that 

 when seeds are taken from the lowlands the alpine characters 

 enumerated are displayed at once as a direct somatic response. 

 When seeds are taken from plants on the elevated plateau where 

 their ancestors may have been for years many or many centuries, 

 (perhaps as long as 2,000 years) and sowed at Vienna and in 

 other cultures, carried through four generations, the leaves lose 

 their xerophytic form and structure but the other characters are 

 retained within the limits of variability. The stems show an 



