64 REPORTS ON INVESTIGATIONS AND PROJECTS. 



COOPERATIVE ARRANGEMENTS. 



Influence of Bnvironic Factors on the Fruiting of Dictyota (by Dr. W. D. 

 Hoyt) : 



The fruiting of Dictyota dichotoma was studied at Naples during March 

 and April, 1910. As was previously observed by Lewis, the sexual plants of 

 this region were found to produce their crops at fortnightly intervals, agree- 

 ing in this respect with the plants of this species on the coasts of Wales and 

 England and differing from the plants on the coast of North California; but 

 the period during which these crops are borne at Naples differs from that of 

 other localities. 



A comparison of Dictyota at Naples with plants of the same species at 

 Beaufort, North Carolina, involving the size of the plants, the relative pro- 

 portion of tetrasporic and sexual plants, the fruiting of the tetrasporic plants, 

 the time taken for a sexual crop to mature, the uniformity of the sexual 

 crop, and the behavior of the vegetative cells of the sexual plants during 

 fruiting shows that in all these respects the plants at Naples more nearly 

 resemble specimens of Dictyota from Jamaica than they do those of the same 

 species at Beaufort. An effort is being made to obtain plants of this species 

 from other regions for comparison with those already studied. 



A study of the liberation of the eggs and tetraspores shows that as there 

 is a definite interval during which the crops of sexual cells is produced, while 

 the tetraspores are borne throughout the month, so there is a definite hour 

 during which the eggs are discharged while the tetraspores are discharged 

 throughout the day. 



The Influence of Environmental Factors upon Beetles in Pure Lines and in 

 Hybridisation (by Prof. W. L. Tower) : 

 The investigations of Prof. W. L. Tower, of the University of Chicago, 

 upon the reaction of the chrysomelid beetles to environmental or climatic 

 conditions have been in charge of Mr. J. B. Breitenbecher during the season 

 1910. Additional cultures have been organized and a system of calibration 

 of climatic factors inaugurated for the purpose of exact determination of the 

 nature of the reactions of the beetles to the unaccustomed conditions. Be- 

 cause of the enforced absence of Professor Tower during the year, a sum- 

 mary of actual progress can not be given. 



The Cactus Flora of the Sonoran Desert (by Dr. J. N. Rose) : 



Exploration was carried on in western Texas, southern New Mexico, and 

 southeastern Arizona, and extended along the Mexican branch of the South- 

 ern Pacific from Hermosillo to Acaponeta. 



About 10,000 specimens, representing 3,000 numbers, were collected. Al- 

 though the expedition was a general one, it was chiefly devoted to the study 

 of the Cactaceae to that region. The most conspicuous plants in the landscape 

 everywhere were the giant cacti, which form great forests extending for 

 hundreds of miles up and down the west coast of Mexico. Of these Car- 



