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POPULAR SCIENCE MONTHLY 



Fig 1. Seed-pans and Seedlings in Pedigreed Cultures in Propagating 

 House, New York Botanical Garden. 



water from a hose, the contact of the nozzle or of the spout of a 

 sprinkler, the careless brushing of the sleeve or the hand against the 

 dirt, may result in the transference of seeds and the vitiation of the 

 results of years of labor and care, especially if a complicated series of 

 tests is under way. 



Having observed all the above precautions, the seeds finally sprout 

 in due time, unfold the seed-leaves and begin development. The 

 remote possibility is to be taken into account that the parental indi- 

 viduals may have been hybrids and that this, the second, generation 

 may illustrate the resolutions, combinations, dominancy and recessivity 

 of the ancestral characters. If, however, no such differentiation be 

 encountered the observer has before him a progeny which by the mul- 

 tiplication of his seed-pans may be made to include as many individuals 

 as might be found in a great geographical area during any season. 

 The accurate examination of this material, and of that offered by suc- 

 ceeding generations may reveal evidence of the highest interest, bearing 

 upon various problems in heredity. It is to be noted that if guarded 

 seeds were not obtained for the beginning of the test, the more impor- 

 tant work must await the second generation under culture for its 

 beginning. 



In even the first examination of the progeny of any physiologically 

 unified strain it will be evident that some diversity of form and appear- 

 ance is present. This variability is generally of the fluctuating type, 

 that is, the entire number of individuals present may be arranged in a 

 series with respect to any quality. Thus, if the one with the narrowest 

 leaf-blades and the one with the widest are placed at opposite poles, the 



