XIV FUNDAMENTAL PROBLEMS ^ 429 



Commencing witli the origin of the flower, which all botanists 

 agree in regarding as a shortened branch, he explains this 

 shortening as an inevitable physiological fact, since the cost of 

 the development of the reproductive elements is so great as 

 necessarily to check vegetative growth. In the same manner 

 the shortening of the inflorescence from raceme to spike or 

 umbel, and thence to the capitulum or dense flower-head 

 of the composite plants is brought about. This shortening, 

 carried still further, produces the flattened leaf-like receptacle 

 of Dorstenia, and further still the deeply hollowed fruity 

 receptacle of the fig. 



The flower itself undergoes a parallel modification due to a 

 similar cause. It is formed by a series of modified leaves 

 arranged round a shortened axis. In its earlier stages the 

 number of these modified leaves is indefinite, as in many 

 Ranunculacea? ; and the axis itself is not greatly shortened, as 

 in Myosurus. The first advance is to a definite number of 

 parts and a permanently shortened axis, in the arrangement 

 termed hypogynous, in which all the whorls are quite distinct 

 from each other. In the next stage there is a further shorten- 

 ing of the central axis, leaving the outer portion as a ring on 

 which the petals are inserted, producing the arrangement 

 termed perigynous. A still further advance is made by the 

 contraction of the axis, so as to leave the central part form- 

 ing the ovary quite below the flower, which is then termed 

 epigynous. 



These several modifications are said to be parallel and 

 definite, and to be determined by the continuous checking of 

 vegetation by reproduction along what is an absolute groove 

 of progressive change. This being the case, the importance of 

 natural selection is greatly diminished. Instead of selecting 

 and accumulating spontaneous indefinite variations, its function 

 is to retard them after the stage of maximum utility has been 

 independently reached. The same simple conception is said 

 to unlock innumerable problems of vegetable morphology, large 

 and small alike. It explains the inevitable development of 

 gymnosperm into angiosperm by the checked vegetative growth 

 of the ovule-bearing leaf or carpel ; while such minor adapta- 

 tions as the splitting fruit of the geranium or the cupped stigma 

 of the pansy, can be no longer looked upon as achievements 



