ColOtfE, fOESi, ANO ftOtBMEN*. 



Fig. 6. Floral diagram of Wallflower. 



same kind of division. But a transverse line still gives 

 a division jnto two equal parts (the line CD) . It divides 

 each of the two stamens 

 into two parts, and sepa- 

 rates the two groups of 

 long stamens, see Figure. 

 But the two halves thus 

 got are not similar to 

 the halves got in the 

 first division. We may 

 call this latter dividing 

 line a secondary halving 

 line. The Wallflower 

 shows bilateral symme- 

 try. Note that we must 

 reckon with the stamens 

 in this case as they enter 

 individually into the plan 

 of the flower. This is not 

 the case where the number of stamens is indefinite. 



The Symmetry of Animals. 



Let us turn now to animals. All higher animals exhibit 

 bilateral symmetry. They have right and left sides. 

 Think, for example, of Mammal, Bird, Frog, Fish, Insect, 

 Crab, etc. G-et examples of animals from pupils. Animals 

 far more than flowers show bilateral symmetry. The 

 animals which show radial symmetry, e.g. jellyfish, sea 

 anemones, starfish, are lower in the scale of being, and 

 there is good reason in this for believing that the bilateral 

 symmetry is the higher type. For with the bilateral 

 symmetry in animals is associated always a definite brain 

 of some sort, marking out the head end. 



It has been suggested with some show of truth that the 

 appearance of varieties of life amongst radial forms, e.g. 

 perhaps certain lowly types of worm, which exhibited one 

 part of their radial margin more sensitive than the rest 

 led the way to forms in which this small beginning 

 developed into a brain a definite ascent. 



