34 



language here used may seem to imply. The usual tran- 

 sition stages occur here as every where else and are 

 exemplified by numerous other plants which were exa- 

 mined but not described. 



Farther, this raised stoma occurs on many leaves 

 where the stomata are sunken in cavities or along furrows. 

 Such are several species of Banksia, Nerium Oleander, 

 Erica, &c. 



In Nerium Oleander which is usually cited as an 

 illustration of an admirable arrangement to prevent too 

 rapid transpiration, the cavities containing the stomata 

 have a much smaller opening than their greatest dia- 

 meter and this opening is covered more or less closely by 

 single-celled thick-walled hairs. The cells lining this ca- 

 vity are extremely thin- walled, stomata raised, numerous 

 thin-walled single celled hairs project into the cavity, 

 which are proved to be living, by applying the salt so- 

 lution, they react at once. Here is an arrangement en- 

 tirely similar to that, of the filz covered leaf of Salvia or 

 Helichrysum, except that the filzig surface is not exposed 

 to the same extent to dew or rain; the only way for 

 moisture from outside to enter, being through the com- 

 paratively small openings which stud the leaf surface. 



Several species of Banksia have a similar structure, 

 such are Banksia serrata L., australis R.B., and integri- 

 folia R.B., also Dryandra speciosa Meisn. In Erica car- 

 nea L. the stomata lying in the ridge or furrow, which 

 runs along the under side of the leaf, are also raised, 

 the epidermal walls are thin, but the hairs are thick- 

 walled and show no reaction on applying salt solution 

 or glycerine. 



One example from the third class of filz-covered 



