138 REVIEW. 



flowered veronica chaeraaedrys, which adorns our banks, woods and hedges so 

 profusely with a carpet of tine blue. This newspecies is a native of California, 

 from whence it was sent by Mr. Douglas. Tbe plants grow about a foot high, 

 producing a terminal raceme of fine blue flowers, each flower being near three 

 quarters of an inch across. It deserves a place in every flower garden. 

 Eutoca from eutoais fruitful, referring to the number of seeds it produces. 



7. GALPHIMIA GLAUCA. Glaucous leaved. [Botanist. 



MALPIGHI ACE.t. DECANDRIA TRIGYNIA. 



This species has been introduced from South America (Mexico we under- 

 stand) by the Rev. Mr. Keen, of Leatherhead, Surry. It is an ornamental 

 Greenhouse shrub, requiring a support similar to a dwarf climber. The 

 flowers are of a bright yellow colour, each being about three quartersof aoi 

 inch across, they are produced in terminal racemes. The pla> t being of 

 easy culture and blooming freely, renders it a desirable plant for the green- 

 house. Galphimla an anagram of Malpighia, a being added for the termi- 

 nation. So named in compliment to Malpighia, an Italian physiologist, &c. 



REVIEW. 



Conl inue d from p. 117. 



" From the same cause, such trees attain a great thickness and live to a 

 great age. The new matter being added externally, has little resistance to 

 overcome (only that of a thin bark, which is easily distended and pushed 

 out) and thus there is hardly any limit to its increase in diameter, while, 

 becoming only more securely fixed as it grows, and the growth going on 

 between the bark and the wood almost independent of the inner parts, there 

 is as little limit to the duration of the tree. In fact, each annual layer ot 

 alburnum and bark seems to have an independent existence — hence trees are 

 often found flourishing, though quite decayed and hollow within." 



Herbaceous or Cellular Integument. This is the layer of cellular 

 tissue, which lies immediately under the epidermis, and gives to the leaves 

 and young stems their green colour. It forms the substance of the leaf, and 

 in it the changes effected on the sap by the atmosphere takes place. 



•' Likf.r, Cortex, or Bark. This is found immediately under the herba- 

 ceous integument, and consists of a vascular net-work, the spaces between 

 the vessels being filled up by cellular tissue. The bark presents concentric 

 layers, composed chiefly of woody fibre and cellular tissue ; and its tissue is 

 easily distended and torn. There is only one layer in young shoots one year 

 old. A new layer of bark is formed in each succeeding year within the old one ; 

 and thus, in trees, the bark is made up of as many vascular layers as the 

 tree is years old ; the older layers being pushed outwards by the growth of 

 the new layers, becoming a lifeless crust, and being often thrown off. Hence 

 the bark may be called endogmous, or growing at its inner surface, 



" In the newly formed layers of bark, the sap, which has been modified in 

 the leaves by the action of the air, descends to nourish and promote the 

 growth of the plant ; hence many of the valuable properties of plants are 

 found in the bark, as in the oak. The outer bark serves the purpose of pro- 

 tecting the new layers of wood and bark from injury, the old and hardened 

 lavers forming an excellent protection from external violence. 



'* The bark, being- the part in which the sap descends to supply the plant, 

 is essential for its increase. If part of the bark be removed from a tree all 

 round, so as to leave the wood bare, the part beneath will not grow, the 

 medium by which the nutritious fluids were conveyed to it having been re- 

 moved, and the tree will ultimately perish. A graft will not take if its bark 

 be not in contact with that of the tree in which it is inserted ; and a branch 

 will not take root when surrounded with earth, if the part be deprived of 

 its bark. 



" The Wood. The wood lies immediately under the bark, and makes the 



