CHAP, in The Morphology of the Flower 97 



1881 : ' As a shoot remains a shoot, and does not lose its 

 morphological dignity, whether it arise as a lateral shoot 

 on the growing point of a stem, or from the embryonic 

 tissue of a foliage leaf (as in many Ferns) , or is adventitious 

 on a root, &c., so also a sporangium remains a sporangium 

 and nothing else, whatever its position ; sporangia are just 

 as much organs sui generis as are shoots, roots, &c.' 



Goebel's views led to the reconsideration of the older 

 theories, and though the latter did not altogether disappear 

 they gained no ground up to the end of the century. The 

 sporangial nature of the ovule on the other hand was almost 

 universally accepted ; its integuments were interpreted 

 by some as homologous with the indusium of the unispor- 

 angiate sorus of Azolla, and by others were regarded as 

 purely adaptive. 



The morphology of the placenta was in its turn the 

 subject of dispute. Schleiden, as we have seen, held it 

 to be axial, apparently because ovules, if they are buds 

 as he said, can only arise on axes. From 1871 for some 

 years onwards, the view of Van Tieghem that the placenta 

 is a portion of the carpel, usually of its margin, met 

 with general acceptance. Among its supporters were 

 Celakowsky and Eichler. Huisgen in 1873 suggested 

 that its morphological value is not the same in all cases ; 

 in the Primulaceae it seems to be a direct prolongation 

 of the stem, and many other orders point, though less 

 strikingly, to the same origin. Though many ingenious 

 theories were advanced to explain away these exceptions 

 to the carpellary theory, they were not very satisfactory, 

 and as the century drew to its close Huisgen's views gained 

 considerable support. 



The details of the development of the ovule were accumu- 

 lating during the latter part of the century. Hofmeister 

 admittedly left them incompletely investigated, though his 

 contributions to the knowledge of them were of the first 



GREEN Q 



