258 Report S.A.A. Advancement of Science. 



I have already incidentally referred to the water-storing- roots 

 of A. filamen/osa and to the water-storing tracheides in this and other 

 species. I will now briefly consider what other provision is found 

 for water-storage and protection from excessive transpiration. 



In none of the species is there developed an epidermal system of 

 water reservoirs such as we find in so many other succulents. The 

 cuticle of the leaves is not particularly thickened, the stomata do 

 not show any provision that could be interpreted as helping to [protect 

 them, except that in A. filamentosa (and perhaps in other species) 

 they are slightly sunk below the surface of the ei)idermis. But all 

 parenchymatous cells of the leaves and also of the cortex of the 

 branches are rich in mucilage, and this no^ doubt is largely responsi- 

 ble for preventing the moisture contained in them being given off loo 

 rapidly. 



The shape of the leaves also helps to a large extent in this direc- 

 tion. It is a fact on which I need not dwell, as it is too well under- 

 stood, that any organ which approaches a spherical form is co ipso 

 well protected against excessive transpiration, as the ratio of surface 

 and contents is so very much more in its favour than in organs which 

 are flattened. In the section Avonia the leaves are exceedingh small, 

 but expose a greatly rounded surface to the atmosphere, while in 

 the section TelcphiasU-iim they actually a])pr()ach more or less the 

 spherical form. 



But all species of Anacampseros are i)articularly well protected 

 externally. They all have wrappers composed of dead tissues, which 

 are practically impermeable to water. I refer of course to the 

 stipules. These behave, however, differently in the two sections of 

 the genus. 



In section Telephiasirum, where their main bodv is composetl 

 of stiff hairs, they close firmly round the buds and the apices of the 

 branches. They then form such a dense felt that transpiration must 

 be reduced to a minimum, if not stopped altogether. In older parts 

 they become so far separated that they can scarcely afford any 

 direct protection, but I find the}- prevent the dewdro])s from running 

 down the plants, and thus no doubt render an indirect service to 

 them, reducing transpiration while the dew is evaporating. I made 

 some experiments with A. pilamentosa in order to see whether dew 

 would actually be taken up by its aerial organs, but the result was 

 negative, or at all events indecisive, though plants kept in a room 

 and occasionally wetted above the ground retained their vitality 

 longer than others \\ hich were not wetted, and even produced small 

 flowers and ripened their seeds, but this could be best explained 

 by a better retention of the moisture in the plant. The long hairs, 

 other than stipular. in this and other species, which are also com- 

 posed of dead cells even before the leaves are fully develoi)ed. evi- 

 dently perform subsidiary services in the same direction. There 

 are. however, in A. filamentosa and other species smaller hairs of 

 peculiar structure which require further investigation. 



The stipules of the species belonging to the section Avonia 

 are developed as comparatively large, leaf-like, flat stnictures. Thev 



