678 Mutations 



to the assumption of independent and parallel 

 mutations. 



For the purpose of a comparison with the 

 Helwingia type we are however, not at all con- 

 cerned with the species to which the trifurca- 

 tum variety belongs, but only with the varietal 

 mark itself. The spikelets may be one-, two- or 

 three-flowered, according to the species. If we 

 choose for further consideration the hexasti- 

 chum type, each spikelet produces three nor- 

 mal flowers and afterwards three normal grains. 

 Morphologically however, the spikelet is not 

 homologous to those parts of other grasses 

 which have the same name. It is constituted of 

 three real spikelets, and thus deserves the name 

 of a triple construction. Each of these three 

 little organs has its normal pair of outer scales 

 or glumae. These are linear and short, ending 

 in a long and narrow spine. Those of the mid- 

 dle-most spikelets stand on its outer side, while 

 those of the lateral part are placed transversely. 

 In this way they form a kind of involucre 

 around the central parts. The latter consist 

 of the inner and outer palets or scales, each two 

 of which include one of the flowers. The outer 

 palet is to be considered as the metamorphosed 

 leaf, in the axil of which the flower is produced. 

 In the common sorts of barley it bears a long 

 awn, giving thereby its typical aspect to the 



