! 



58 



INHERITANCE. 



Chap. XIII. 



in the mammalian series, has likewise been attributed, perhaps 

 truly, to reversion. 65 ' 



When 



or peloric, the change is generally looked at by botanists as a return to the 



primitive state. But Dr. Maxwell 



X y , WiM . w o-twio CVIL/XJ uiouusstJU IlllS 



subject, remarks that when, for instance, all the sepals of a Trop&olum 

 become green and of the same shape, instead of being coloured with one 

 alone prolonged into a spur, or when all the petals of a Linaria become 

 simple and regular, such cases may be due merely to an arrest of deve- 

 lopment ; for in these flowers all the organs during their earliest condition 

 are symmetrical, and, if arrested at this stage of growth, they would not 

 become irregular. If, moreover, the arrest were to take place at a still 

 earlier period of development, the result would be a simple tuft of green 

 leaves ; and no one probably would call this a case of reversion. Dr. Masters 

 designates the cases first alluded to as regular peloria; and others, in 

 which all the corresponding parts assume a similar form of irregularity, as 

 when all the petals in a Linaria become spurred, as irregular peloria. We 

 have no right to attribute these latter cases to reversion, until it can be 

 shown to be probable that the parent-form, for instance, of the genus 

 Linaria had had all its petals spurred ; for a change of this nature might 

 result from the spreading of an anomalous structure, in accordance with 

 the law, to be discussed in a future chapter, of homologous parts tending 

 to vary in the same manner. But as both forms of peloria frequently 

 occur on the same individual plant of the Linaria, 67 they probably stand 

 in some close relation to each other. On the doctrine that peloria is 

 simply the result of an arrest of development, it is difficult to understand 

 how an organ arrested at a very early period of growth should acquire its 

 full functional perfection ;— how a petal, supposed to be thus arrested, 

 should acquire its brilliant colours, and serve as an envelope to the flower, 

 or a stamen produce efficient pollen ; yet this occurs with many peloric 

 flowers. That pelorism is not due to mere chance variability, but either 

 to an arrest of development or to reversion, we may infer from an observa- 

 tion made by Ch. Morren, 68 namely, that families which have irregular 

 flowers often " return by these monstrous growths to their regular form ; 

 whilst we never see a regular flower realise the structure of an irregular 



one. 



}> 



Some flowers have almost certainly become more or less completely 

 peloric through reversion. Gorydalis tuberosa properly has one of its two 

 nectaries colourless, destitute of nectar, only half the size of the other, and 



65 Isid. Geoffroy St. Hilaire, < Des de Teratologic' 1841, pp. 184, 352. 



Anomalies,' torn. iii. p. 353. "With 



<* Verlot, 'Des Varietes,' 1865, p 



respect to the mammae in women, see 89; Naudin, 'Nouvelles Archives du 



torn. i. p. 710. 



Natural 



66 



Hist. Eeview,' April, 



Museum,' torn. i. p. 137. 



68 In his discussion on some curious 



1863, p. 258. See also his Lecture, Koyal peloric calceolarias, quoted in ' Journal 

 Institution, March 16, 1860. On same of Horticulture,' Feb. 24, 1863, p. 



subject, see Moquin-Tandon, ' Elements 



152. 



& 



