IIORIZONTAI. OR TRAXSVER3E AXD PERPENDICULAR 

 SECTION, OF THE STEM OF AN EXOGEX OF THKEE YEAR's 



GROWTH. Ill the center of each is seen tlie pitli, a, 

 compojiec) of cellular tis<ue ; surroiuidiiig ii is the me- 

 dullary sheath, 6,- and exterior to it are tli.ee rings of 

 •wood, each consisting of c, c, dotted ducts, and iJ, ri, 

 ^v•oody fibre. The last o.med is in contact with the 

 barli, e, e, in which tlie layers are indistinct. Carpen- 

 ter's Vegetable Pliysivlogy. 



HORIZOXTAL AND VERTICAL SECTION OF THE STEM 



OF AN Endogen, showing the bundles of ducts, woody 

 fibre, and spiral vessels, irregularly disposed through 

 the whole stem, a, a, portions of cellular tissue ; 6, 6, 

 spiral vessels ; c, c, doited ducts ; d. rf, woody fibre. 

 The cellular portion of the skin. M-hich in Exogcns is 

 separa ed by the first introduction of wond into pidi and 

 bark, liere remains permanently intermingled Witli it. 



[The accompanying engraving,-;, representing sections of Exogcn and Endogen, will ex- 

 plain themselves. The number of zones in trees will probabl}' give a tolerable approxima- 

 tion to the years of growth in temperate climates; but even here, two may be formed in 

 one year, if any great check of the groAvtli suddenly occurs during the summer. In tro- 

 pical climates the indication is far more doubtful; Adanson's computation, made in this 

 way, carried the age of the Baobabs to from 5000 to 6000 years. It has been stated that 

 monthly rings are formed in the tropics of South America, (f/op/cms' Rcssarches in 

 Magnetism.') Some plants, such as the Cacti and Cycadese, require more than one year 

 for the formation of a zoue of wood.] 



CHEAP VINERIES AND GREEN-HOUSES. 



Not a few of those who dabble in horticulture in various parts of the country, would 

 be glad to borrow the assistance of a little glass in raising a good crop of foreign grapes, 

 a few green-house plants, or the like, but are prevented by the cost of the thing in the 

 ordinary way. If they talk to the carpenter about even a small "green-house," say 20 

 or 30 feet long, he gives them an estimate of some 300 or 400 dollars — and as this is more 

 than they can rightly afford, they let the matter drop. 



Some mode, then, is wanted by persons of moderate means, of putting up a building of 

 a simple and cheaper description — call it what you please — for it will aim to be useful — 

 not ornamental — some plan that will enable us to get as fine foreign fruits, grapes, figs, &c., 

 or as healthy and beautiful plants, as the most costly building, glazed with the best plate glass. 



Such buildings as these have larely been put up in this country — though there are occa- 

 sional examples in the premises of some of the market florists about our cities. We have 

 already spoken, (p. 184, v. 5.) of large ranges of this kind, which Are saw last summer 

 in the nurseries of jNIr. Rivers, Sawbridgeworth, England. In these buildings, put up at 

 less than half the cost of ordinary green-houses, we saw plants of all kinds, and fr 

 various sorts, all in the highest possible health and productiveness. 



