288 SCIENCE PROGRESS 



plump, and may be as many as five on the spikelet. It is 

 commonly grown in the Mediterranean district and is found 

 in India. Although its quality is poor, it gives good crops 

 and is therefore cultivated in England ; it is the commonest 

 bearded wheat we grow. Polish wheat is characterised by a 

 marked development of the outer or involucral glumes, which 

 are often an inch long and enclose all the flowers in the 

 spikelet; the grains are very long and hard. It is probably 

 ancient, as it is represented in Abyssinia by several marked 

 races, but it is not mentioned till the seventeenth century. It 

 gives poor yields, and is grown only in Abyssinia, Italy and 

 Spain. Kcernicke recognises it as a mutation from T. duriim^ 

 while Schweinfurth shows that T. durum and Emmer had a 

 common origin. Stapf has traced this origin to T. dicoccoides, 

 a wild wheat found by Aaronsohn in Palestine. 



The third division, economically much the most important, 

 comprises all the common ordinary wheats grown for bread- 

 making and grouped together as T. vulgare. Some of these 

 are bearded, others not : bearded varieties usually predominate 

 in hot, dry countries, and beardless ones in colder climates. 

 The chaff may be red or white and the flour strong or weak. 

 There is evidence that it is very ancient : some of the grains 

 found among neolithic remains in Europe appear to be T. vulgare. 

 This wheat has probably the same origin as T. compactum — the 

 dwarf wheats, still grown in Germany, Switzerland, Turkestan, 

 and India, the common ancestor being probably a small stout- 

 grained wheat coming from Syria or Mesopotamia. So far, 

 however, this ancestral form has not been discovered. 



The fourth division consists of the Spelts. As was the case 

 with Einkorn, the grains of Spelts do not readily detach them- 

 selves from the chaff; hence they do not thrash out like 

 T. vulgare. Gradmann has adduced evidence to show that 

 Spelt was the ordinary cereal of the Alamans, a group of 

 Germanic tribes from whom the Romans obtained it. On the 

 northern shores of the Black Sea there still occurs a species 

 of ALgilops cylindricum or Triticum cylindricum, which seems to 

 have been the original form of the Spelts. 



The Conditions Regulating the Growth of Wheat 



In order that any plant may make satisfactory growth, six 

 general conditions must be fulfilled. There must be sufficient 



