6o REPORTS ON INVESTIGATIONS AND PROJECTS. 



Alterations in Heredity Induced by Ovarial Treatment (by Dr. D. T. Mac- 

 Dougal) : 

 The methods previously described have been extended to cover a wide 

 range of species and with the use of additional reagents. A large number 

 of progeny derived from treated ovaries are under observation, but no new 

 announcement of results may be safely made. So far, derivatives in Oeno- 

 thera, Raimannia, and Penstemon have been found and tested, while aberrant 

 individuals in Echinocereus (formerly Cereus) have been secured. The new 

 form in Oenothera has been found to be normal, self-maintaining, and per- 

 sistently different from the parent. 



Acclimatisation: the Inductive Influence of Climatic Complexes upon Organ- 

 isms (by Dr. D. T. MacDougal) : 

 A large number of selected plants are being grown in the plantations at 

 the Desert Laboratory, in the Santa Catalina Mountains, Arizona, and at 

 Carmel, California, and somatic alterations are being induced under condi- 

 tions suggestive of the actuating causes. The heritability of such changes 

 and exact determinations of the reactions constituting the alterations are 

 being carried out. 



The Water-balance of Succulents (by Dr. D. T. MacDougal) : 



An extensive series of measurements of massive cacti, chiefly in situ, was 

 carried out by Mrs, E. S. Spalding, and an equally extensive series of weigh- 

 ings of other plants was made by D. T. MacDougal, for the purpose of deter- 

 mining the part played by the water-balance in the growth and survival of 

 these plants. A sahuaro (Carnegiea) i8 feet high holds nearly 200 gallons 

 of water in its cylindrical trunk ; the depletion and repletion of this water- 

 balance takes place very rapidly and is influenced by sunlight, temperature, 

 etc., in such manner as to be accompanied by some striking changes in form 

 and size. 



The presence of a great surplus of water in all parts of the plant has one 

 singular consequence in the matter of the survival of living branches on dead 

 trunks. The trunk may die and decay quickly by a black-rotting process 

 which leaves the bare woody skeleton holding aloft the green branches, 

 which are a few inches in thickness and may be several feet long. These 

 branches may survive for a year, during which time they produce flowers as 

 well as fruit. Whole and uninjured individuals of cacti may carry on some 

 growth and live for two or three years upon their accumulated balance of 

 water, while other species are known which carry sufficient surplus to meet 

 their needs for ten or fifteen or perhaps twenty-five years. 



The rate of loss of plants exposed in the open may be as much as four 

 to eight times that of plants in inclosed but well-ventilated rooms, in which 

 the direct action of the wind and sun are eliminated. This is apparent even 

 when the plants tested in the shade were much larger than those in the open. 



Observations on a number of specimens show that some gain in weight 

 may be expected in small specimens of Bchinocactus detached and kept in 



