576 Journal of Agricultural Research voi.xix.No.it 



of this description he obviously had the heterozygous intermediate or 

 a mixture of this and the homozygous intermediate, since he obtained all 

 types from the seeding. Later, the homozygous form seems to have been 

 isolated. In 1883, Drechsler of Gottingen sent Rimpau an intermediate 

 which he had found in a field of H. disiichon palmella zeocriton and which 

 apparently bred true from the time of its discovery. Both Rimpau (6, 7) 

 and Komicke (4) observed the intermediate. According to Komicke's 

 statement of 1885, he found the intermediate as an accidental hybrid in 

 a field of 2 -rowed winter barley. At first the selection was heterozygous, 

 but, according to the statement of his son (5), in 1908, it later became 

 constant. Both Rimpau and Kornicke made mass selections which 

 evidently included heterozygous forms, at least at first. It is probable 

 that homozygous types were eventually obtained. 



These four cases of probable isolation of the fixed intermediate all 

 occurred before 1900 and, therefore, before the importance of plant selec- 

 tions in hybrids was generally recognized. It is worthy of note that all 

 four were instances where accidental hybrids were observed, rather than 

 the products of any of the numerous crosses made by those investigators. 



The history since 1900 is more surprising than that previous to 1900. 

 The modern methods of breeding lead to the direct and ready isolation 

 of this type, yet, so far as the authors know, it has not been reported. 

 Since 1900, indeed, two plant breeders who have worked extensively 

 with barley have assumed that a fixed intermediate does not occur in 

 crosses between 6-rowed and 2-rowed barleys. Von Tschermak {8) says 

 as late as 191 4 that the intermediate form with fertile lateral florets is 

 heterozygous and, therefore, is never constant. Biffin (z), while not so 

 sweeping in his statement, must have held a similar view. In 1907, he 

 reported nine crosses in which a homozygous intermediate might occur. 

 From the Fj progeny of one of these he selected a considerable number 

 of intermediates of two types and planted them. All proved to be hetero- 

 zygous. He did not test the progeny of the other crosses but assumed 

 that they would behave in the same way. In the discussion he then 

 states : 



The heterozygote, therefore, of forms with hermaphrodite staminate lateral florets 

 is potentially hermaphrodite and of the type known to systematists as H. intermedium. 



In 1907 J. H. Wilson (9) reported an Fj generation of Standwell X 

 Bere, in which he made the following observation: 



Examples occurred in which the grains of all six rows were fully developed, but the 

 lateral ones were without awns. 



In this case Mr. Wilson probably noticed the homozygous type. It is 

 interesting that he should have used as the 6-rowed parent the variety 

 of barley in which Haxton found the first recorded intermediate. 



The observations of theseniorauthorinthesestudies extend overthepast 

 10 years. In the summer of 1909 he made a large number of hybrids on 

 the grounds of the Minnesota Agricultural Experiment Station. A con- 



