184 HALF-AN-HOUR AT 



part of the story of the wood of the Yew. In examining wood, 

 it is desirable to make a transverse section first ; this furnishes a 

 key to what structures are to be looked for. Then, if the bark be 

 present, take a thin piece of the outer layer of cells (epiderm, of 

 authors) ; the form of the cells composing it, their contents, and 

 the presence or absence of stomata are to be remarked. Then, if 

 the bark contain liber-fibres (the tissue constituting hemp, flax, 

 and the like), a longitudinal section to display them is requisite. 

 Another longitudinal section, just a little within the outer ring of 

 wood, follows; this is called a '^vertical taugeiital section" ; it 

 yields important facts as to the medullary rays and the woody 

 fibres in one aspect. Lastly, a thin longitudinal section is made 

 right through the centre, parallel to the medullary rays ; this is 

 called a '■'vertical radial" section. Building the facts obtained by 

 these means into a whole, a complete idea of the structure of any 

 wood is obtained. The rich red-brown resin, so commonly met 

 with in Coniferous wood, is well shown in some of the cells, 

 notably in those of the outer bark (ectophloeum). The stem from 

 which this was cut had taken twelve years in its formation, and 

 illustrates well the slow rate of growth in the Yew. It is 

 interesting also to note the great eccentricity in the various rings — 

 the narrow portion had a north aspect ; the wide parts of the 

 rings, the south. Then look at the inner portion of each ring 

 towards the pith. In the spring of the year, after the winter's 

 sleep, vegetation makes a sudden bound. The first-formed cells 

 are large, with their long diameter from within outwards, indicating 

 rapid formation. As the year wanes, the vigour of growth 

 diminishes. The relative diameters of the cells are reversed ; 

 growth and sap-elaboration are more perfect ; the cells form more 

 slowly ; have thicker walls ; and then comes the period of hyber- 

 nation again, when growth absolutely ceases ; the record of that 

 year's work is completed, and sharply marked out. Given the 

 year in which the wood was cut, we might read off the meteoro- 

 logical conditions of that and the preceding eleven years : — some 

 favourable to vegetation, others so much the reverse, that scarcely 

 has the history of any work been added to the record. 



It would have been specially desirable here to add the two 

 vertical sections named, because in the Yew the wood has a very 

 uncommon structure, viz., a beautiful spiral fibre in addition to 

 the so-called " glandular " appearance, ordinarily, though not quite 

 correctly, supposed to be specially characteristic of Coniferous 

 wood. The real distinction of such wood is the absence of pitted 

 ducts and spiral vessels. Fossil wood having the structure of 

 Yew may occasionally be found in Coal ; the late Joseph Jackson 

 Lister had a fine piece in his collection, from which he was good 

 enough to allow me to take a drawing. 



