REVERSION IN PARTHENOGENESIS 141 



groups of red branches among the many white ones " (De Vries, 

 1905. P- 167). This case is peculiar, however, because the white 

 variety is propagated only by cuttings or grafting. " If this is 

 true, all specimens must be considered as constituting together 

 only one individual, notwithstanding their wide distribution in the 

 gardens and parks of so many countries. This induces me to sup- 

 pose that the tendency to reversion is not a character of the variety 

 as such, but rather a peculiarity of this one individual " (p. 168). 



Wheat-ear Carnations. — Large beds of carnations sometimes 

 show peculiar anomalous forms known as " Wheat-ears," with 

 small green ears instead of flowers. There has been a loss of flowers 

 and a multiplication of bracts. On a specimen of this De Vries 

 observed that some branches reverted wholly or partially to the 

 production of normal flowers. " The proof that this retrograde 

 modification was due to the existence of a character in the latent 

 state, was given by the colour of the flowers. If the reverted buds 

 had only lost the power of producing spikes, they would evidently 

 have returned to the characteristics of the ordinary species, and 

 their colour would have been a pale pink. Instead of this, all 

 flowers- displayed corollas of a deep brown. They obviously reverted 

 to their special progenitor, the chance variety from which they had 

 sprung, and not to the common prototype of the species " (1905, 

 p. 229). 



A Picturesque Case. — The long-headed green dahlia originated 

 twice from two different double-flowered varieties — a deep carmine 

 with white tops on the rays, and a pale orange known as " Sunrise." 

 They were quite sterile and were progagated asexually, one in 

 Prof. De Vries's garden, the other in the nursery at Haarlem, where 

 both arose. " In the earlier cultures both remained true to their 

 types, never producing true florets. No mark of the original differ- 

 ence was to be seen between them." But in 1903 both reverted to 

 their prototypes, and bore ordinary double flower-heads. " Thus 

 far we have an ordinary case of reversion. But the important side 

 of the phenomenon was, that each plant exactly ' recollected ' 

 from which parent it had sprung. All of those in my garden re- 

 verted to the carmine florets with white tips, and all of those in the 

 nursery to the pale orange colour and the other characteristics of 

 the ' Sunrise ' variety " (1905, p. 231). It seems impossible not to 

 admit that characters of the parent-varieties had lain for a time 

 latent and had eventually reasserted themselves. 



