Mutations in Horticulture 623 



mulated in preceding generations. An interest- 

 ing case is afforded by a sterile variety of corn, 

 which originated some time ago in my own pedi- 

 gree-cultures made for another purpose, and 

 which had begun with an ear of 1886. The first 

 generation from the original seeds showed noth- 

 ing particular, but the second at once produced 

 quite a number of sterile plants. The sterility 

 was caused by the total lack of branches, includ- 

 ing those bearing the pistillate flowers. The 

 terminal spikes themselves were reduced to 

 naked spindles, without branches, without flow- 

 ers and even almost without bracts. 



Only in some individuals this negative charac- 

 ter was seen to give way at the tip, showing a 

 few small naked branches. Of course it was 

 impossible to propagate this curious form, but 

 my observations showed that it sprang into ex- 

 istence from known ancestors by a single step 

 or sudden leap. This leap, however, was not 

 confined to a single specimen; on the contrary 

 it affected 40 plants out of a culture of 340 

 individuals. The same phenomenon was re- 

 peated from the seeds of the normal plants in 

 the following year, but afterwards the mon- 

 strosity disappeared. 



The Italian poplar affords another instance. 

 It is considered by some authors as a different 

 species, Populus italica, and by others as a 



