.CARBOHYDRATES 145 
Carbohydrates.—Con. taste and dialyze easily. The 
solubility and sweetness as 
well as power to dialyze 
decrease as the number of car- 
bon atoms increases. Those 
with C, (or Cs) are called 
monosaccharids; with Cy, di- 
saccharids or bioses; Cis, tri- 
saccharids or trioses; Co, 
tetrasaccharids or _ tetroses; 
those with larger value of car- 
bon are often termed poly- 
saccharids. They usually have 
the formula (CgHi00s)n. 
Monosaccharids. Only the commoner forms 
will be mentioned. 
Arabinose Obtained by treatment of 
C;Hi00;, (CH.(OH)—(CH- various gums with dilute 
(OH)); -CHO) boiling H.SO,. 
d-Glucose (grape sugar, dex- This is the commonest sugar. 
trose) It is in most cases the first car- 
C.H1206, (CH.2(OH)—(CH- bohydrate produced in pho- 
(OH)),—CHO) tosynthesis. It occurs abun- 
dantly in most sweet fruits. 
It is the form in which carbo- 
hydrates are translocated. 
d-Galactose (formula as for glu- Produced by the splitting of 
cose) the lactose, raffinose, or man- 
neotetrose molecule by weak 
acids, therefore one of the 
constituents of these sugars. 
d-Mannose (formula as for glu- Produced by the splitting of 
cose) the molecule of certain (re- 
serve) celluloses by weak acids 
and therefore one of the con- 
stituents of those carbohy- 
drates. 
d-Fructose (fruit sugar or levu- This sugar is abundant in 
lose) many sweet fruits, e.g. grape. 
CsHi206, (CH2(OH) — (CH- 
(OH))s —-CO—CH;(OH)) 
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