MASTEES' BOOK ON VEGETABLE TEKATOLOG-Y. 



159 



the ordinary type. This lower scale, which in other varieties of barley 

 bears the awn, here forms an inverted flower-bud upon its midrib. It is 

 three-bbed at the summit. The central lobe is oblong and hollow, form- 

 ing a kind of hood and covered with hairs. In its cavity the super- 

 numerary floret is developed. Ordinarily there is only one, and that is 

 rudimentary, but sometimes two or three of them are seen, each belonging 

 to one of the three lobes of the scale. 



The three lobes are to be considered as shortened awns or as a three- 

 lobed appendix representing the awn. The length of these awns is highly 

 variable, and this quality is perhaps the most striking in the variety. 

 They often reach only 1-2 mm., or the majority may become longer and 

 attain even one centimetre, while here and there, between them, longer 

 ones are inserted, extending in some instances even as far as 3 cm. from 

 the spike. Their transverse position, in such cases, is strikingly con- 

 trasted with the ordinary erect position of the awns. 



The accidental flower arises at some distance beneath the summit of 

 the scale on its middle vein. The development begins with the protrusion 

 of a little adventitious scale and the flower itself is situated beneath this 

 scale, protected by it, and the primary scale, and in this way turned upside 

 down. The stamens occur in varying numbers ; typically there are three 

 of them, but, often, only one or two are developed. The ovary is situated 

 in the middle of the flower and in some instances it has been seen to ripen 

 into a little seed. All these deviations conform to a single type, and it is 

 very probable that all of them have originated in the manner of a single 

 varietal mark. Their high degree of variability may then be compared 

 with that of variegated leaves or of double flowers. 



Another case of an hereditary anomaly is that of the peloria of the 

 ordinary foxglove (fig. 44). Barely is a malformation an isolated pheno- 

 menon ; almost always it is associated, from the operations of cause or 

 effect, with some others. A change, slight in itself, often acquires impor- 

 tance from its combination with other alterations. This is particularly 

 well seen in the case of the peloriated foxglove. Fission of the corolla, 

 petaloid stamens, supernumerary petals often transformed into narrow 

 tubes and sometimes situated on the outside of the corolla, are some of 

 the many secondary malformations. Increase of number is another, and 

 this is perhaps the most striking feature of this variety. The corolla is 

 enlarged, bordered by twelve or more lobes instead of the normal number 

 of five, and the number of stamens is increased in the same way. Finally, 

 proliferation adds to the complexity of the flower. Within its ovary, 

 small green leaflets often take the place of the ovules ; and after the 

 fading away of the corolla, they grow and burst the ovary wall and 

 protrude from it, forming a green tuft of bracts. In other cases, the axis 

 of the peloric flowers elongates itself through the middle of the ovary and 

 develops into a new spike with quite a number of normal flowers, some- 

 times even producing at its summit another peloric structure which may 

 then repeat all the anomalies. 



In different places in his book, Masters has pointed out the necessity 

 of assuming an influence of two sets of causes on the development of 

 monstrosities. One set is internal, the other external. 



Internal causes are those inherent in the organization of the plant. 



