A MORPHOLOGICAL STUDY OF NAIAS AND 

 ZANNICHELLL\. 



BY DOUGLAS HOUGHTON CAMPBELL, 



Professor of Botany, Leland Stanford funior University. 



CONTENTS. 



Page. 



Pirates I-V. 

 A. — Naias. 



I. The Growing-Point of the Stem 8 



II. The Leaves lo 



III. The Roots ii 



IV. The Flowers 12 



1. The Male Flower 12 



(a) Development of the Pollen 14 



(Jb) The Germination of the Pollen 17 



2. The Female Flower 17 



V. Pollination 23 



VI. Fertilization 24 



VII. The Embryo 25 



VIII. The Cotyledon 30 



IX. The Stem 31 



X. The Root 31 



XI. The Endosperm 34 



B. — Zannichellia. 



I. General Morphology 37 



II. The Stem-Apex 38 



III. The Roots 40 



IV. The Male Flower 40 



V. The Female Flower 42 



VI. The Embryo 48 



VII. The Cotyledon 5° 



VIII. The Stem 50 



IX. The Root 50 



X. The Endosperm 51 



XI. The Fruit 52 



Summary and Conclusions. 



A.— Naias 52 



B.— Zannichellia 53 



Supplementary Note 59 



Bibliography 60 



Explanation of Plates 62 



1 1 ] June 4, 1897. 



