56 The Plant World. 



what care and regularity the young plants are arranged. The 

 designation of the various plants is shown by means of carefully 

 labelled boards, which as here shown, are arranged in a line 

 through the center of the beds. Even in spite of all the care and 

 precaution that can be taken in preparing the soil and protecting 

 the primroses, nevertheless some of the plants are often attacked 

 and killed by a kind of worm just about the time the plants, 

 after much time and work have been bestowed upon them, are 

 about ready to show the results of the experiment. At the left, 

 in Figure 1, are shown five primroses with paper bags tied 

 over the flower part. These bags allow the passage of light, 

 and protect the flowers from the visitations of insects during 

 experimentation. The bags are carefully tied at the lower end 

 about the flowers. Each year a great many primrose plants 

 are planted and experimented upon. The keeping of the records 

 of this vast number of plants, and the hundreds of polhnations 

 performed each year by Professor de Vries, requires a vast 

 amount of work, or "bookkeeping," as he once expressed it, 

 to keep all the records clear and in a usuable form. 



Figure 2, shows Professor de Vries in his primrose garden. 

 The photograph was taken of the left-hand corner of the garden 

 near the green house shown above. 



PLANT ASSOCIATIONS OF THE DESERT LABORATORY 

 DOMAIN AND ADJACENT VALLEY. 



By V. M. Spalding. 

 (Continued from February Number.) 

 (4) Salt-Spots; Assocl\tion of Salt-Bushes. 

 The description already given holds in all its general features 

 for the soil and vegetation of the flood-plain of the Santa Cruz 

 River, but certain areas, some of which approach the neighbor- 

 hood of Tumamoc Hill, are so exceptional in character as to call 

 for a special account. 



The so-called salt-spots include areas varying from a few 

 rods to many square miles in extent, and are widely distributed 



