JOINTS. 53 



In the nodes the cells are small, filled with protoplasm, and 

 retain their nucleus. From the nodes are developed all 

 organs and accessory parts. Presented by II. Groves, Esq. 



B. 31. Portion of the stem of Equisetum maximum with whorls 

 of branchlets cut short. The stem is hollow from the more 

 rapid growth of the circumference than the centre. It is 

 jointed, being divided into nodes from which the branchlets 

 spring, and from which all organs are formed. At the 

 nodes the vascular bundles communicate with one another, 

 and a septum is formed across the cavity of the hollow stem. 



Royal Gardens, Kew. 



B. 32. Three portions of the stem of Wheat (Triticum vulgare], 

 with leaves attached. The stem is hollow from the rupture 

 of the pith. At the nodes a septum separates the neigh- 

 bouring cavities ; at this point the vascular bundles of the 

 leaf (veins) are continued into those of the stem (cauline 

 bundles). Presented by Prof. C. Stewart. 



B. 33. Terminal branch of Yellow Jasmine (Jasminum nudi- 

 florum). The stem is solid owing to the pith not being 

 ruptured. The insertions of the leaves indicate the nodes. 



Presented In/ Prof. C. Stewart. 



Joints that allow of continuous growth. 

 ANIMALS. 



B. 34. Two specimens of the test (corona) of an Echinus (E. 

 acntus). They are about half-grown. One has been bi- 

 sected, the other has had the five sets of ambulacral, and 

 five sets of interambulacral plates detached. One of each of 

 these has had each plate separated. There are 82 plates 

 in each ambulacrum, and 46 in each interambulacrum ; 

 the total number in the test, including the 10 apical plates, 

 being 650. Each plate enlarges by additions to its borders 

 their number being increased by the formation of fresh 

 plates at the apex of the test. 



Presented by Prof. C. Stewart. 



