VARIATION 357 



zygote speltoid epidermis, since they gave only normal progeny. From 

 the fourth example some of the grains produced speltoid heterozygote 

 plants which segregated in the ratio of i : i. In this type one or more 

 subepidermal cell-layers from which the gametic cells arise were evi- 

 dently heterozygote. 



I have never observed white-chaffed and red-chaffed ears or white- 

 grained ears and red-grained ears upon the same plant, but plants are not 

 infrequently seen bearing fully-bearded and almost beardless ears upon 

 the same individual, the fully-bearded ears being always found on the 

 first- formed culms. 



Plants possessing both " clubbed " and lax ears of uniform density 

 are not infrequently met with at Reading, the lax ears being borne on the 

 youngest straws. Rimpau observed both long lax ears and short denser 

 Squareheads upon an F x plant of the hybrid 



Frankenstein (lax-eared vulgar e) x Igel (compaction), and Caron- 

 Eldingen also describes and figures a plant possessing both lax and 

 " clubbed " ears of two different types which he explains as resulting 

 from a twin grain (p. 359). 



Possibly some of these variations may be manifestations of natural 

 reduction of vigour or inadequate nutrition of the later-formed " tillers " 

 of the plants and hardly to be classed as examples of bud sports. 



Ohlmer, Preul, and others attribute the clubbing of the ears of Square- 

 head wheats to an excess of nitrogen and diminished water-supply in the 

 early stages of development of the culm and ear, and my own observations 

 support this view. 



TERATOLOGICAL SPORTS. Besides the sports which are concerned 

 with the discontinuous variation of the normal characters of the wheat 

 plant, there are teratological sports, " monstrosities " or " freaks " pos- 

 sessing abnormal features, such as twin ears, supernumerary spikelets, 

 and other examples mentioned below. 



They are comparatively rare and their cause unknown. 



i. BENT AND SINUOUS UPPER INTERNODES. In some individual culms 

 the upper internodes are bent completely round so that the ear is parallel 

 with the straw and its apex downwards. In others the upper internode 

 is sinuous just beneath the ear. Both these malformations are more 

 frequent in T. turgidum and T. durum than in other races, and are often 

 seen in the deformed progeny of hybrids between distinct races (Fig. 

 220). 



ii. MALFORMED UPPER INTERNODE AND LEAF. A common deformity is 

 the arrested development of the upper internode of the culm, the first 

 node being less than an inch from the base of the ear. In such cases the 

 ear is usually normal, but the uppermost leaf is more or less malformed, 



