242 



THE AMERICAN NATURALIST [Vol. LIII 



suits according to the theoretical starchy-sweet ratio. 

 The results obtained and corrected in this way are as 

 follow^s : 



The numbers are small, but the distribution obtained is 

 clearly different from a 9:3:3:1 ratio. The agreement 

 with the nearest theoretical results, assuming linkage, is 

 close (Pr— .615). The per cent, of crossing-over, 8.3, in- 

 dicated by tliese figures is low. In the other cases of 

 linkage reported, the percentages of crossing-over were 

 much higher, 25.7 per cent, in the waxy endosperm- 

 aleurone color combinations and 20 per cent, in the 

 aleurone color-chlorophyll color combination with the 

 exception of the one ease where complete linkage has so 

 far been found. 



In making the clnssificatimi nil of llic ).laiit> which 

 showed the tunicate chai'actcr. whether nf the hairtiini- 

 cato or full-tunicate typo, wcic .-ia— cd as tunicate, as con- 

 trasted to the normal ])laiii-. Scmcual ion was clear ))e- 

 tween these two class(>- and their \\a- little possibility of 

 confusion even when the ear- were innnature. On the 

 other hand, it was not always easy to distinguish full- 

 tunicate from half-tunicate plants, as the tassels of the 

 former class do not always produce seed, and the ears, 

 which are quite characteristic wlieii fully doveloi>ed, are 

 not so distinct when inunatui-e. and many of those ]-»lants 

 were late in matui'ing. Any ei-ror ot" cha-^ilieation here 

 does not affect the linkau'o re~iilt<. however. Tliero is one 

 source of error in that llie ph'inf^ Hickeiv.l iirot'nsely; 

 many of tliese bore ears an<l ta— eU aini weiv difficult to 

 distinguish from the main Mad<. 'Idie piant- \\ei'(> o-rown 

 in hills, and when classifying them it was not always pos- 



