THE PATH OF DEGENERATION IN PLANTS 197 



the first few leaves formed in the seedling remain 

 rudimentary, aud serve only to protect the axillary 

 buds (tig. 68, leaves 1 and 2). Contrasted with 

 the condition in L. tenuifolius, although all the 

 vetches had probably a common ancestor, these 

 primary leaves have three little projections, the 

 two lateral of which are reduced stipules. 



We do not know of any vegetable example of 

 recapitulation in the case of an organ reduced by 

 arrest of development. Plants exist, however, 

 which after having produced leaves of typical 

 structure begin to produce leaves the development 

 of which remains arrested. Such a plant is the 

 Acacia which bears phyllodes. At first the leaves 

 are like those of other Acacias ; next it bears leaves, 

 the blades of which are rudimentary ; and finally 

 leaves with normal stipules, but with no trace of 

 lateral leaflets on the petiole. 



In this case the ancestral conditions are known 

 and are quite different. 1 



2. Organogeny of flowers. What we have said 

 about leaves applies to the organogeny of flowers. 

 Here also in the cases of atrophy produced by 

 arrest of development there is no indication of 



1 Many other reduced plant organs might be instanced, such as 

 the stipules of Sambucus or the teeth of the calyx, in many Com- 

 positse and Umbelliferae. After their formation such organs grow 

 very slowly and exhibit no trace of recapitulation. This happens 

 with the leaves of Sempervivum (fig. 49). Without doubt these 

 leaves are derived from leaves normally divided into hypopodium 

 and epipodium, but they show no trace of this division. 



