band 6 ZENTRALBLATT FÜR ZOOLOGIE HEFT 5 

 ALLGEMEINE UND EXPERIMENTELLE BIOLOGIE 



Vererbung-, Variation, Mutation. 



391) Harlan, H. V., Some Distinctions in our Cultivated Barleys witk 

 Reference to Their Use in Plant Breeding. In: U. S. Dept. Agr. Bull. 

 No. 137, S. 1—28, Oct. 1914. 



This is a biometrical study of Variation in barley (Hordeum sp.) from the 

 standpoint of testing the value of various characters for the practical plant breeder. 

 The detailed conclusions cannot be reviewed in brief space. Some of the more 

 important results from a general biological standpoint are these: Strains are often 

 shown to be distinct in early grovvth by their rate of development. Leaf 

 production is, in some ways, a varietal character. In some varietie3 the third leaf 

 appears in three days after the second, while in others it occurs six days later. 

 In the production of the fourth leaf even a greater ränge exists. The emergence 

 of the awn has been found to be far more accurate and more easily obtained 

 than the date of heading. The precocity of the strain at the time of the emer- 

 gence of the awn is a heritable character. The date of ripening is less dependable 

 than the emergence of the awns. A comparison of the development during all 

 stages serves to reveal many differences not apparent when each stage is taken 

 separateiy. The degree of exsertion of the spike is sometimes a varietal character 

 but is not often useful. The number of culms per plant is to some extent a varie- 

 tal character, but selections are so affected by season and location that it is very 

 difficult to use the density of the spike may easily be made the basis of many 

 separations. The established taxonomic groups based on relative fertility were 

 found to be invariable under all extremes of American cbmate. The natural varieties 

 in the deficiens group'of Abyssinian barleys seem more extensive than most 

 classifications have indicated. From barleys of this same region a group with 

 a peculiar habit of floret abortion has b^en isolated. 



A study of the pigmentation of barleys leads to the following conclusions: 

 There are two coloring materials in barley: One, anthocyanin, is red in its acid 

 and blue in its alkaline condition; the other, a melanin-like Compound, is black. The 

 pigments may occur in the hulls, the pericarp, the aleurone layer, and occasionally 

 in the starch endosperm. The resulting colors of the grain are quite complicated. 

 White denotes the absence of all pigment; a heavy deposit of the melanin-like 

 Compound in the hulls results in black; a light deposit, brown. Anthocyanin in 

 the hulls results in a light violet-red. In naked forms the melanin-like Compound 

 in the pericarp results in a black kernel; anthocyanin produced a violet one. The 

 acid condition of anthocyanin in the pericarp superimposed upon the alkaline 

 condition in the aleurone beneath a colorless pericarp is blue-gray. While hulls 

 over a blue aleurone cause the grain to appear bluish or bluish gray. Black hulls 

 over a blue aleurone give, of course, a black appearance. The anthocyanin is 

 always violet in the hulls and in the pericarp, showing that these tissues are in 

 an acid condition, and always blue in the aleurone layer, showing an alkaline 

 condition. The occurrence of anthocyanin in the pericarp of hull-less barleys is 

 more significant than its production in the aleurone layer. Pearl. 



Zentralblatt f. Zoologie, allgeni. u. experim. Biologie. Bd. 6. 11 



