BOT.— Vol. I.] CAMPBELL— NAIAS AND ZANNICHELLIA. 37 



which is also included the genus Althenia, and this view is 

 probably borne out by a study of the facts of structure and 

 development. 



In his careful study of the morphology of Zannichellia^ 

 Schumann has given a review of the literature bearing upon 

 the subject and refers to the early work of Irmisch, who 

 was the first to make a detailed account of this plant. Eich- 

 ler, in his " Bliithendiagrammen " (1875, P- i)j also treats 

 briefly of the morphology of this plant; and most recently 

 of all, there are some brief references to the structure of 

 the female flower in a paper by Magnus (1894, PP- 222, 223) 

 called out by Schumann's work. Beyond those references 

 the writer is not aware of any other accounts of the plant, 

 beyond the ordinary ones in the descriptive manuals. 

 Even in the work of Schumann, which is much the most 

 complete so far as the flowers are concerned, no attention is 

 given to the histology, which has apparently never been 

 examined at all. 



In studying the development of the tissues of the young 

 vegetative organs and flowers, the same methods were used 

 as in Naias, and the results given were mainly obtained from 

 series of microtome-sections. 



I. General Morphology. 



Schumann (1892, p. 155) has made a very careful study of 

 the arrangement of the stem, leaves, and flowers, and has 

 shown that the only way to understand clearly their real rela- 

 tionship is to study the history of their development. While 

 he succeeded in correcting some of the errors of the earlier 

 observers, he himself failed to reach a clear understanding 

 of the relation of the flowers to the main axis of the plant, 

 from failure to study sections of the youngest stages. He 

 showed conclusively that the anther was a truly terminal 

 structure, as in Naias, but the group of carpels, which, in 

 common with Magnus, he is inclined to consider as a single 

 flower, he concludes to be the transformed apex of the 

 main axis, a view which, as we shall see, is not borne out by 

 a study of the youngest stages. 



