54 



as 



a< 



In morphology this important symmetry is commonly regarded 

 that of bilateral-symmetrical forms. As such, innumerable leaves 



(vine, oak, etc.), and flowers 



(Papillionaceae, Orchidaceae, 



Labiates, of Fumaria, etc.) 



are representatives of this 



class. In fig. 55 some flowers 



of this kind: Paphiopedilum 



Hookerae(d); Galeopsis dubia 



(a); Lamium purpureum(b) ; 



Brunella grandiflora(c) ; Dal- 



housiea bracteata(e) ; Cyclopia 



genistoides(f); Podalyria cor- 



data (g), have been reprodu- 



a 



7TL 



Fig. S3- 



Fig 54- 

 Potassium- 

 tetrathionate. 



ced as typical examples of the said symmetry, 

 to bring back this well-known fact to memory. 

 It may be remarked here as a very im- 

 portant fact that almost all the higher living beings (man, qua- 

 drupeds, birds, insects, etc.) have the symmetry of the group S, 

 being a single plane of reflection 

 their only symmetry-element. 

 The lower animals on the con- 

 trary (Blastoidea, Corolla, Ra- 

 diolariae, Discomedusea, Asci- 

 diae, etc.) often show a much 

 higher symmetry characterised 

 by. axes of high period-numbers 

 (n 4, 5, 6, etc.), and by the 

 presence of several planes of 

 symmetry. In this respect it 

 would appear as if a striking 

 contrast were present in the 

 evolutionary development of li- 



ving and of so-called inanimate 

 matter. For in the domain of 

 crystallography generally the 

 holehedral classes of each sys- 



Fig. 55- 



Galeopsis dubia. b. Lamium purpureum. 

 c. Brunella grandiflora. d. Paphiopedilum 



Hooker ae. e. Dalhousiea bracteata. f. Cy- 



. . . . , . , , , . ^ ntn 



clopia gemstoides. g. Podaiyna cordata. 



tern show an incomparably 



greater number of representatives than the hemihedral and tetarto- 



hedral classes, and it was therefore suggested by some crystallogra- 



