CHAPTER III. 



DEVELOPMENT. 

 ORGANOGENY AND EMBRYOLOGY. 



If it were not for the long hairs which clothe the apex of the stem of 

 Nymphaea, there could hardly be a more favorable object for the study of 

 the development of the organs of a mature plant. We cut off the broad 

 tip of a rhizome of JV. alba, odorata, or tuberosa i cm. back and pin 

 it down to the wax bottom of a dissecting pan. Then with the aid of 

 a dissecting microscope the larger leaves and their stipules are cut away. 

 The hairs may be pulled out with fine forceps. This is the most difficult 

 part of the task. Finally one discovers that the stem apex is slightly basin- 

 shaped. At the center is a very minute elevation, the growing point, and 

 around it the rudiments of leaves and flowers are arranged in spiral order. 



The figures of leaf development given by Payer (1857) for N. alba are 

 equally applicable to N. odorata, and would need but little alteration for 

 N. rubra. I have examined the last two by dissection, and have studied 

 N. caerulca, odorata, and flava briefly in serial microtome section. The 

 youngest rudiments at the stem apex are mere rounded papillze, without 

 indication of their future destiny. They gradually elongate and on reach- 

 ing a length of 0.08 cm. the foliar or floral character becomes evident. 

 The leaf rudiment (cf. PI. II, 1-7) takes on a more and more conical form, 

 while the floral rudiment remains broad and rounded and develops the 

 anterior sepal. A leaf of N. rubra var., 0.16 cm. long, is about three-quar- 

 ters as wide at base, and tapers to a rounded apex ; on the inner face a 

 broad triangular depression is sharply marked off by two lateral ridges 

 which are continuous over the apex and curve inward a little below, ending 

 about one-fifth of the length of the rudiment above its base. Below this 

 is the petiole ; the upper part is the lamina. The rudiment becomes 

 longer and more acute, and the lateral ridges become slightly rolled 

 inward until in a leaf 0.3 cm. long the former triangular depression has 

 become a narrow groove, rounded above. At the base of the petiole there 

 is now on either side a narrow rounded auricle, three times as long as 



