712 



It sometimes occurs in the wood and sometimes attacks the parenchyma and 

 bast cells of the bark. The first stages of the disease are found in the 

 resinosis of the wood; the mature condition consists in the formation of 

 large quantities of uniform resin masses in cavities in the trunk and branches, 

 which are usually called resin boils. It is well known that resin in the cell 

 contents normally occurs in the form of drops or, as in the glue mats of 

 many wood buds, in the intermediate lamellae of the cell wall, or finally, as 

 in our pines and spruces, in definitely distributed, peculiar resin canals. The 

 contents of many parenchyma cells near the resin canal show resin drops 

 and starch grains, of which some not infrequently are provided with a resin 

 coating. The immediate surroundings must necessarily furnish the sub- 

 stances which fill the large resin pockets. Whether this material is trans- 

 ported in the form of resin, as N. J. C. Miiller^ assumes, or in the form of 

 some other compound and is only developed into resin where it is found as 

 such, which theory Hanstein- is inclined to believe, is of little importance 

 for our consideration. In this we have to maintain that the formation of 

 considerable amounts of resin and gum is possible only through the transfor- 

 mation of a plastic substance, flowing toward those places where tine 

 liquefaction takes place, i. e. a positive loss of sap. To this it should be 

 added for resinosis, as for gummosis, that the existing plant substance, in 

 the form of wood and bark tissue and of starch grains, succumbs to lique- 

 faction and that, in this way, considerable material is lost. According to 

 investigations made by Karsten'' and \\'igand', the wood at first seems 

 resiniferous, i. e. saturated with resin and balsam. In most of the cells of 

 this saturated tissue, the resin appears as a wall coating, or as drops which 

 have spread together until the cells seem completely filled with the mass. 

 The walls of the cells, originally thick, become thinner and thinner in the 

 same degree as the amount of resin increases within the cell, until, finally, 

 only a fine outline is left, which is gradually lost in the mass of resin. 



As in gum exudation, the medullary rays also seem to be longer 

 resistent, since they are clearly seen to extend into the uniform resin mass 

 of the dissolved wood cells surrounding them. For complete analogy in the 

 two processes, there is lacking only the proof that, in the exudation of 

 resin, an abnormal wood parenchyma is formed, which undergoes absolute 

 resinosis. 



1 Miiller (tJber die Verteilung der Harze usw. in Pring.sheim's Jahrb. f. wiss. 

 Bot. 1866 — 67, p. 387 ff) says the great amount of resin in the resin ducts cannot 

 have reached tliat place except by penetrating many cell walls. He finds the ceil 

 walls to be permeable for resin. Thin cross sections of pine wood left lying for 

 some time in water showed that all the resin in the cell walls has been rc^placed 

 by water. 



2 Hanstein (Uber die Organe der Harz- and Schleimabsonderung in dem Laub- 

 knospen. Bot. Zeit., 1868, No. 33 ff.) speaks of the occurrence of resin first in the 

 grooves of secretion cells as small bands between the cuticle and the cellulose mem- 

 brane. This is undoubtedly an important reason for assuming that "the resin, which 

 occurs in the form of intermediate wall layers, first assumes its real character after 

 it has passed through the cell wall in another form and been deposited as an inter- 

 mediate layer." 



3 Karsten, H. tJber die Entstehung des Harzes, Wachses, Gummis und Schleims 

 durch die assimilierende Tatigkeit der Zellineml)runen. Bot. Zeit. 1857, p. 310. 



•« Wigand, tJber die DesoiKanisalion der rflanzenzcHc. I'rin.t;sheiin's .Jahrb. f. 

 wis.s. Bot. Vol. HI, p. 165. 



