PRINCIPLES OP PLANT-TEIiATOLOGY. 



process by which the structures concerned become 

 freed from the restraint of congestion and reduction 

 into which they have been brought in the course of 

 evolution. Hence we may truly say that this process 

 is a reversionary one. 



As we should expect, and as Masters appositely 

 points out, proliferation is most frequent, on the whole, 

 in plants or groups whose inflorescences or whose 

 flowers have become less severely congested and reduced 

 in the course of evolution, namely, in those with in- 

 definite inflorescences, or with flowers whose axis is, in 

 one part or another, normally somewhat elongated, e. g. 

 the inflorescences of Cruciferse and Leguminosse, the 

 owers of Cruciferge, Primulacese, and CaryophyllaceaB. 

 And axillary proliferation tends to be more common in 

 groups some of whose members are normally branched 

 in the inflorescence. 



There are cases of proliferation which we may regard 

 with certainty as representing the exact condition of 

 the ancestry of the plants concerned, as in the caules- 

 cent abnormality of the common primrose ; for the 

 inflorescences of the vast majority of this order are of 

 this caulescent type. On the other hand the extreme 

 forms of floral proliferations are obviously new struc- 

 tures, unheard of in the immediate ancestry of the 

 plants affected. In other instances where we cannot 

 presume with certainty that the proliferation is a 

 reversion to a character in the immediate ancestry, jet 

 when we find that the abnormal feature occurs as a 

 perfectly normal one in other closely allied members 

 of the group, it no longer assumes a strange and un- 

 natural appearance, and in such cases the reversion 

 theory is probably much more applicable than any 

 other. For example, the abnormal branching of the 

 spike in Plantago major and P. lanceolata finds its 

 counterpart in the normally branched inflorescence 

 of such species as P. Gynops and P. Psyllum. 



The abnormally -branched inflorescences of the rye- 

 grass (Lolium) are but reproducing a character which 



