14 



of the darkened fibers change in color and very soon have a snoxv- 

 white appearance. At first this point is a mere spot, but it gradually 

 expands and in a short time attains a length of several inches (PL I), 

 the longitudinal growth being more rapid than the lateral. Around 

 this point an area of several inches of wood is changed to cellulose, 

 and now the total absorption of some of this cellulose begins and a 

 small cavit}' starts and gradually increases in size. About this time 

 white spots, similar to the first one, appear in the heartwood at a 

 point from 3 to 5 feet on either side of the first hole — that is, the 

 mj'celium of the fungus has grown longitudinally and set up two new 

 centers of destruction. A vigorous growth of the hyphte takes place 

 at these centers, and this growth invades the wood in all directions and 

 brings about the characteristic changes very rapidly. In due time 

 other centers arise farther up and down the trunk. The older holes 

 continue to increase in size until they attain their greatest proportions, 

 reaching the lateral limit ver^^ soon, as the}' are rarely more than 2 to 

 3 inches wide. The cavities extend up and down and frequently 

 unite. The absorption of the cellulose goes on until none is left. 

 The walls of the cavities then become coated with the brown felt of 

 h3'pha3 before mentioned, or the second form of decay may have set 

 in, leaving fine plates of wood hanging from the surfaces. 



The setting up of these centers at which the destruction of the wood 

 takes place is very difficult to account for, and at this time no expla- 

 nation can be^-iven of the singular mode of action. It was at first 

 thought that the centers might be due to separate infections, but it 

 was soon proved that this was not the case, as the hypha3 were absent 

 from the outer laA'crs of wood. A case which to some extent resembles 

 the one under consideration is that of a recenth" described disease of 

 Taxodium,^ in which there is similar local action of the m\'celium. 

 The cavities in this case are ver}- close to each other, and it seems 

 probable that a product formed from the wood b}' the fungus might 

 play an active role in limiting the growth of the mycelium to certain 

 areas. Further work on this part of the subject is in progress. 



THE FRUITING BODY. 



After decomposition has advanced sufliciently the fruiting bod}" 

 forms on the outside of the trunk. This body does not appear to be 

 common, for as far as known it has been collected only twice, once in 

 1895, by Miss Sadie F. Price, at Bowling Green, Ky., this specimen 

 being now in Prof. L. M. Underwood's herbarium, and once by the 

 writer near Murfreesboro, Tenn.^ Nothing is known of its develop- 



^von Schrenk, H., A disease of Taxodium disiichuin known as peckiness, etc. 

 (Eleventh Annual Report Missouri Botanical Garden, 1899) . 



-The description here given is based on these two specimens and may have to be 

 modifieil when more specimens are studied. 



