JANUABT 20, 1911] 



SCIENCE 



97 



to the standing of the new types may be 

 reached but slowly. 



The important results of Tower, in which 

 new types and various hereditary depart- 

 ures in the Leptinotarsse were induced by 

 the action of climatic factors on the germ- 

 plasm, have been so fully described and re- 

 peatedly cited that any further description 

 is unnecessary at the present time. 



Gager produced chromosomic irregulari- 

 ties by the exposure of ovaries of CEnothera 

 to radium emanations a few years ago and 

 some of the progeny from treated parents 

 were aberrant, but the transmissibility of 

 the new characters was not tested. By the 

 use of similar excitations Morgan has re- 

 cently induced the appearance of white 

 eyes and short wings in the fly, Bro- 

 sophila, which characters seem to be fixed 

 and fully transmissible. Both are sex- 

 limited and Mendelize when paired with 

 red eyes and long wings. 



Woltereck's cultures of Daphnia have 

 yielded some facts of unusual interest in 

 the present connection. The particular 

 group of this crustacean furnishing the 

 experimental material is taken to be very 

 variable, and it was subjected to over- 

 feeding, with the immediate result that the 

 variability of the form of the head ap- 

 peared to be widened, the size of this 

 structure being increased. This disap- 

 peared when lots from the cultures were 

 restored to normal conditions in the earlier 

 stage of the work. After three or four 

 months of over-feeding, the form of the 

 head came within narrower limits, and 

 fewer aberrants were seen, while lots re- 

 turned to normal conditions, showed a 

 slower restoration of the original form of 

 the head. Two years after the cultures 

 were begun, it was found that the original 

 head form was not displayed by young 

 restored to normal nutrition conditions, 

 the larger helmet being persistent. It 



seems fairly certain that a new genotype 

 resulted from the long-continued action of 

 the culture medium, which must have in- 

 fluenced the soma and germ-plasm con- 

 temporaneously. 



Klebs, who has long been concerned with 

 the morphogenic reactions of plants, has 

 determined a series of conditions under 

 which stages of mycelial development, 

 asexual, zoospore and sexual or oospore 

 formations in filamentous fungi may be 

 inhibited or variously interchanged. Much 

 more 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 deviations in question 

 were found to be transmissible in guarded 

 seed-reproductions. 



Lastly we now have the fortunate ex- 

 periences of Zederbauer with Capsella 

 which has yielded some conclusions of ex- 

 ceptional importance. A genotype of 

 Capsella hursa pastoris resembling tarax- 

 acifolium 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 to a plateau 

 at an elevation of 2,000 to 2,400 meters, 

 along which the plant has been carried by 

 man, and in this elevated habitat it has 

 taken on certain alpine characters, includ- 

 ing elongated roots, xerophytic leaves, 

 stems 2, 5 cm. high, reddish flowers, with a 

 noticeable increase of the hairiness of the 

 entire plant. That the distributional his- 

 tory has been correctly apprehended seems 

 entirely confirmed by the fact that when 

 seeds are taken from the lowlands the 



