Eversporting Varieties. 23 



The remarkable fistulous and monophyllous varieties, so 

 well known as examples of partial atavism, are further 

 instances of eversporting types (Vol. I, Fig. 38, p. 193, 

 and Fig. 15 of this volume), together with the viviparous 

 grasses {Poa alpiiia vivipara, Poa bulbosa vivipara, etc.) 

 and a number of other viviparous forms such as Agave 

 vivipara and so forth. ^ If the constant variety corre- 

 sponding to a certain intermediate race does not exist, 

 this latter is usually classed as a variety in the case of 

 middle races, but as a heritable anomaly in the case of 

 half races. 



It is, further, very probable that many natural spe- 

 cies which attract attention by the high degree of vari- 

 ability of some particular character are really in a way 

 intermediate races, i. e., that they owe their multiformity 

 to the co-existence of two antagonistic characters. In- 

 stead of entering further into this very attractive subject 

 I shall content myself wnth citing the case of Acacia 

 diversifolia which owes its name and its nature to the 

 conflict between the two characters of bipinnate leaves 

 and flattened petioles without leaflets (phyllody of the 

 stalks). 



The question of the constancy of these intermediate 

 races is a very important one. I propose to deal with 

 it when referring to individual cases in detail; and the 

 only general statement I shall make now is that both con- 

 stant and inconstant intermediate races exist. On the 



« 



one hand there are those cases in which an overstepping 

 of the limits between these two races is apparently as 

 rare as the mutations by which new species arise, and 



^ See GoEBEL, Organographie, I, pp. 153-159; E. H. Hunger, 

 Uchcr cinigc vivipare Pflauccii. Diss. Rostock, 1887. Bot. Jahresber., 

 t888, T. XVT, 1, p. 421. and also, especial!}', Clos, in Actcs du congrcs 

 international dc botaniquc, Paris, Sept., 1900, p. 7. 



