PACHYMA COCOS. 203 



wood of a very pale colour, but it presents a totally different iseo. 

 appearance under the microscope. It consists of what appears 

 to he a mass of mycelium, the threads of which have forced 

 their way through the substance of the wood in every direction, 

 separating the cells and converting them into irregularly-shaped 

 bodies of a highly refractive nature, having a good deal the ap- 

 pearance of starch-granules, but without any concentric mark- 

 ings, and exhibiting no reaction with iodine. A section of this 

 portion is shown in PL IX. Fig. 7. The remaining parts of the Plate IX. 

 specimen, marked c and d, and which constitute the main portion 

 of the Pachyma, bear a general resemblance, when seen under 

 the microscope, to the section shown in Fig. 7 ; but the compo- 

 nent bodies vary more in size and many of them attain larger 

 dimensions : the mycelium also is far less plentiful. A reference 

 to PL IX. Fig. 8 will show the form of a few of the latter bodies, 

 a combination of which with tissue, such as that shown in Fig. 7, 

 constitutes the mass of the Pachyma. We entertain no doubt 

 that the bodies shown in PL IX. Fig. 8 are of the same nature 

 as those in PL IX. Fig. 7, i.e. they are wood-cells, in a more 

 advanced state of disease and distortion. If it is wished to Description of 

 examine the threads or mycelium separately from the substance 

 of the Pachyma, it may be done by selecting a specimen such as 

 that shown in PL X. Fig. 9, in which the substance is traversed 

 by cracks. It will then be seen that (at least in some specimens) 

 the opposite walls of the cracks are united by masses of white 

 woolly fibres ; and by taking a small quantity of the wool in 

 forceps, and placing it under the microscope, it will be seen to 

 consist exclusively of delicate threads entirely free from the 

 irregularly-shaped starchy-looking bodies forming the mass of 

 the Pachyma. These threads are similar to those in PL IX. 

 Fig. 7, and are, we suspect, of fungoid origin ; and although we 

 see no reason to doubt that the Pachyma is in the main (as has 

 been long supposed) only an altered state of the root of the tree> 

 we .think it highly probable that that altered state is the effect 

 of fungoid disease, and that all the threads above alluded to may 

 be the mycelium to which the disease is due. The section shown 

 in PI. X. Fig. 6 exhibits at one end, at the points e, a brown 



