OF NAIAS GRAMINEA, VAR. DELILEI. 47 



of the leaf; the bifurcating end of one cell encloses the 

 solitary attenuated end of. the one next to it; a section at 

 such a junction severs the three interlocked ends of two 

 contiguous cells. 



The absence of this libriform tissue in the Lancashire 

 plant has a bearing in determining its sourcCj as will be 

 noticed further on. 



Between the Italian and the Lancashire plants I notice 

 one other point of difference, which may be due to the 

 period of growth. Above and below the central bundle of 

 the leaf, but particularly on the lower surface, the external 

 cells of Malinverni^s specimens from Vercelli are densely 

 packed with starch-grains, very similar to what is met 

 with in the external membrane of the fruit. Although 

 starch-granules are present in the membrane of the fruits 

 of the Lancashire plant, I have failed to discover a single 

 instance of their occurring in quantity in the leaves. 



All the cells of the leaf exhibit a very striking circu- 

 lation of their contents against the cell-walls ; the chloro- 

 phyllean granules and other protoplasmic bodies being 

 very large, and the cell-walls being very transparent, the 

 plant furnishes a splendid illustration of circulation, more 

 than any plant which I have examined. 



IX. The Inflorescence. 



The construction of the flowers of the genus Naias 

 and their morphology have been minutely studied by 

 Dr. Magnus, and the results given in his 'Beitrage,^ 

 pp. 26-33. I^ referring to the development of a side- 

 shoot of N. graminea, he says that many of the internodes 

 are suppressed, and that from three to five pairs of leaves 

 spring from the axis before we reach the flowers, which 

 occur to the number of from two to four all in one node. 



