1 1 14 Michell . — On the Comparative Anatomy of the 
C. gariepina . 
This species resembles the former in all its outstanding features. The 
following differences, however, must be noted : 
(a) The mucilage cells are less numerous, and only occur in the cell 
row immediately below the epidermis. 
(b) The crystals of calcium oxalate are more numerous, and the larger 
clusters occur in the cells of the mesophyll as well as below stomata. 
Crystal-blocked stomata are more frequently found in this species, about 
20 per cent, of the stomata possessing the crystals. 
The leaf of Ceraria affords a good example of the xerophytic structure 
so common in plants growing in dry regions. The size and shape of the 
leaf are to be noticed in this connexion. In Ceraria the xerophytism is 
more pronounced than in the allied genus Portulacaria , and the differences 
which exist between the leaves of the two genera are correlated with 
this fact. 
B. Stem. 
C. gariepina. 
The most striking feature in a transverse section is the broad band of 
dark-brown mucilage cells occurring in the cortex. This ring does not 
appear to be found in the other genera of this order. 1 The stem is sur- 
rounded with a thick bark, an account of which is given below. 
Cortex. In the cortex there are three distinct bands of tissue (Fig. 4). 
Next the bark are large water-storing cells, separated from one another by 
radial bands of parenchyma. The mucilage band occupies the greater part 
of the cortex, and consists of large mucilage-containing cells interrupted 
here and there by small parenchyma cells. The innermost layer of the 
cortex consists of ordinary ground tissue with groups of sclerenchymatous 
cells immediately opposite the bundles. 
Endodermis. The endodermis is not marked. 
Stele. The vascular bundles are arranged in a ring, and are very similar 
to those of Portnlacaida afra, the chief difference in the vascular cylinder 
being that in Ceraria three or four of the medullary rays are broader than 
the rest. There are about twenty open bundles of the usual collateral type, 
and in the oldest stem available three faintly marked annual rings could be 
distinguished (Fig. 6 ). 
Phloem. The phloem is characterized by a great development of 
fibres on the outer side of each phloem mass. All elements of the phloem 
have an extremely small transverse diameter, and for this reason the 
separate elements are difficult to identify. The sieve plates occur on both 
the lateral and the end walls of the sieve-tubes, but owing to their small 
size, and the difficulty experienced in obtaining microtome sections, their 
1 Solereder (’08), p. 112 (6). 
