258 PLANT ANATOMY. 
always perfectly uniform, they often become disturbed in con- 
sequence of the laceration of the individual tissues. 
Hand in hand with the organic transformations just described, 
there occur, in the surroundings of the passages, certain chemi- 
cal processes, to which the resins, volatile oils and varieties of 
mucilage owe their origin and also the special form which 
enables them to pass into the intercellular spaces. The resins, 
namely, are either dissolved involatile oils, as ** balsams” or ‘‘ tur- 
pentines,” or they are emulsified by mucilage (gum). It is only 
in this form that they are capable of passing through the cell- 
walls into the passages formed for their reception. Although 
the manner of formation of the cells and tissues’ which 
have here been considered may appear quite clear, yet the 
chemical side of these processes has so far not been elucidated. 
In many cases, resin and volatile oil appear to be produced from 
amylum. If this may be accepted with some degree of probabil- 
ity, the equally just supposition is forcibly presented that under 
certain conditions cellulose, which agrees with amylum in its 
composition, is also capable of undergoing the same transforma- 
tion. Asa matter of fact, this is also the case with the lysigenic 
canals, which have previously been considered (compare page 
248). 
According to Frank’s investigations,’ it would appear as if 
the oil-tubes or stripes, vitte@,* which are so characteristic for 
many of the umbelliferous fruits, first became forced asunder 
through the volatile oil which makes its appearance in them, 
while the balsam-passages of umbelliferous roots present the 
development illustrated by Figs. 169 to 175. But in many of 
these fruits the oil-tubes also show remnants of transverse walls 
(Fig. 183) which presumably indicate a solution of original 
boundary cells. The effloresced appearance of the tissues which 
surround the oil-tubes in Fructus Carvi, Fructus Feniculi, 
1 Especially described by Miiller, loc. cit., p. 387.—Thomas, Ibid., 
_v., p. 48.—See also Frank, ‘‘ Beitrage zur Pflanzenphysiologie,” Leipzig, 
1868, pp. 120, 123. 
_ ** Beitr. z. Pflanzenphysiologie,” p. 128. 
sss 8 Fig. 94 0.—Berg’s “ Atlas,” Plates xli., xlii., xliii. 
