EUDESMIN AND ITS DERIVATIVES. 453 
With regard to the central portion of the molecule the first 
point to notice is the function of the oxygen atoms. The 
negative experiments detailed in the experimental portion 
conclusively demonstrate the absence of hydroxyl or car- 
bonyl groups. Both oxygen atoms have, therefore, ether 
function. The absence of ethylene linkages is also proved, 
and, if these conclusions be accepted as accurate, then an 
inspection of the above formula will show that this central 
portion of the molecule must contain two closed rings in 
_ order to account for the number of hydrogen atoms below 
the saturation capacity. Now there are six carbon atoms 
and two oxygen atoms, altogether eight atoms which could 
be members of a ring structure, and from this it follows 
that if the rings be separate the number of members in the 
two rings will be five and three or four and four—in either 
case a very improbable supposition. The rings are, there- 
fore, fused as in naphthalene and the possible systems will 
then be seven fused with three, six with four, or five with 
five. The latter is clearly the most probable in view of 
the almost complete absence of three and four membered 
rings from natural products. The following formula indi- 
cates a probable constitution for eudesmin 
Me O O 
a tbe 
Me O  Teaeee iis oa O Me 
CH2—OH ee: O Me 
Soph. iad, 
O 
although there is no evidence for the position of the vera- 
tryl rests, and the following ring systems are alternatives 
to the one figured above :— 
O O O 
je / s / \ _oCON 
O00 0 O0-O\Y Oe pe nisi, So 
