DEPARTMENT OF BOTANICAL RESEARCH, 



63 



The great water-reserves of desert plants have value in making for en- 

 durance of arid seasons, yet it is notable that many species may not carry 

 on growth or reproduction if the water-balance is depleted very much. The 

 total losses and fate of a number of massive plants taken from the soil and 

 placed on suitable supports in a laboratory and in the open are given below. 



Alterations in Heredity Induced by Ovarial Treatment, by Dr. D. T. 



MacDougal. 



The cultures in which progeny derived from treated ovaries are being 

 tested through three and four generations now include Bchinocereus fend- 

 leri, Echinocactus wisliseiii, Brodicca capitata, Fouquieria splendens, Sphce- 

 ralcea pedata, Penstemon wrightii, Phytolacca decandra, Opuntia discata, 

 Carnegiea gigantea, Amsinckia spectahilis, and Solanum elecegnifolium. Of 

 these, lots from successive seasons are under observation from two species, 

 in which some species are represented by two or more different treatments. 



The announcement was made in 1908 that some divergent characters were 

 seen in a treated progeny of Cereiis. The plant in question, by the inces- 

 sant changes of nomenclature, is known at the time of this writing as 

 Bchinocereus fendleri. The progeny is coming into bloom, and while one 

 of the individuals diverges widely beyond the observed range of fluctuating 

 variability, it can not yet be definitely stated whether or not the characters 

 displayed are permanently heritable or not. This is to be determined by the 

 behavior of the descendants of the second and third generations. 



The derivative of Oenothera biennis, first obtained in 1905, has now been 

 tested to the fifth generation, hybridized with the parental form, and culti- 

 vated under the most diverse conditions. No reasonable doubt as to its 

 character remains. 



Experimental studies such as are here described lead the investigator into 

 the consideration of two phases of the subject. One is concerned with the 

 demonstration of induced hereditarv alterations and the studv of their be- 



