86 VIEWS OF THE MICROSCOPIC WORLD. 



ELM. A section of an Elm branch which appears, is an exceeding rich figure, 

 and the several divisions are boldly defined. The skin of the bark possesses consid- 

 erable thickness, and the pores of the cellular tissue belonging to this integument 

 are exceedingly small. 



Throughout the bark, bundles of the proper vessels are seen profusely scattered 

 in oval or egg-shaped clusters, and beyond it the sap-wood. In .the true wood, the 

 annual rings are very distinctly marked. The vessels dispersed through the wood 

 differ very much in size ; the larger, disposed in circular bands, are arranged on the 

 inner margin of every annual ring, while others are scattered promiscuously through- 

 out the wood, and are more numerous near the centre of the section than in the 

 more recently formed wood towards the margin. The more minute vessels are seen 

 stretching in delicate and broken chains across the rays of cellular tissue, emanating 

 from the centre: the various positions of the rays being indicated by the white lines 

 in the figure running from the pith and penetrating for some distance into the 

 bark. The rays of cellular tissue possess great uniformity in their respective thick- 

 nesses, as well as in the intervals by which they are separated from one another. 

 The rays are usually arranged at equal distances from each other. 



ENGLISH WALNUT. In drawing 133 is displayed a magnified section of a branch 

 of English Walnut, four years old, and which presents a most beautiful configura- 

 tion. A B indicates the position of the skin of the bark, and the latter envelope, 

 with its cellular tissue, and proper vessels, is comprised within the space A B C D. 

 The proper vessels collected together in round clusters are distributed in two 

 circular rows H I and R S, deeply situated within the bark. The wood is included 

 in the space D C E F. The first annual ring extending from E to 0, the second 

 from to M, the third from M to K, and the fourth, including the ring of sap-wood, 

 P D, from K to D. The sap-vessels distributed through the wood are not numerous, 

 but their size is comparatively great, and, as in the Elm, they are grouped more 

 thickly together near the pith, the cells of which are quite large compared with 

 those of the pith of the Elm. The pith itself is also much larger than in many other 

 woods of the same age. The radial lines of cellular tissue in the Walnut observe 

 no uniformity in respect to their relative thickness, as is the case of the Elm, 

 neither are they arranged at equal distances from each other. 



But the most remarkable peculiarity in the Walnut is the broad white arched 

 bands running across the rays of cellular tissue, four of which are exhibited in the 

 figure before us; in the Elm they are also seen disposed in a similar manner but 

 much narrower. Their existence is attributed to the same circumstances that 

 cause a similar appearance in the Oak ; namely, the greater compression of the cel- 

 lular tissue where these bands occur than in other portions of the wood. 



ASH BRANCH. A cross section of part of an Ash is a handsome object when 

 magnified to a considerable extent. The bark consists of an infinite number of 

 cells formed by the cellular tissue. Within the bark, next to the skin and nearest 

 to the wood, clusters of minute vessels extend in two circular rows from side to 

 side. The arrangement of the radial insertions of cellular tissue is very beautiful ; 

 the rays diverging from the pith to the bark at equal distances from each other, and 

 maintaining, nearly always, the same size. The position of the large spiral vessels 



