368 
the urine does not always contain galactose, i.e. that modification 
which, according to us, the kidney is permeable to? Is it perhaps 
just this form which is used in the building up of the cerebrosides? 
This will have to be determined by further experimentation. 
Lastly, before leaving the galactose, it may be interesting just to 
call attention to this: viz., how slight the difference in structure 
between the «- and g-forms is, which difference is concerned with 
their retention or non-retention. 
Thanks especially to the researches of Emin FiscHer (l.c), ALBERDA 
VAN EKENSTEIN, BOESEKEN*), to which also correspond those of 
BourquELor’), it must be assumed a little in contravention to the 
current idea, that the structural formulae of the two forms of galac- 
tose can be represented as follows: 
-H—C—OH | _OH—C—H 
ete oan wy Hel on sie 
„0 
Bee ele 4 OHG ser on 
ee 
CZH ne 
HEC=SOH Ea 
CH:OH CH:OH 
ERLE 3-(y-)d-galactose. 
From these formulae it appears that here mutatis mutandis the 
retention is exclusively dependent upon the relative places of the OH 
and H with regard to the first asymmetric C-atom. 
The partial retention of Laylose. 
The thought of the explanation given in the previous paragraph 
for the partial retention of the ‘galactose solution occurred to us 
when it was noticed that also xyiose-solutions were subject to partial 
retention. Corresponding to this is the fact that, like in glucose- 
solutions, also in xylose-solutions two modifications could be sepa- 
rated by Tanret. Also in the case of xyloses Emit Fiscurr could 
separate two glucosides, or xylosides rather, an «- and a 8-form, for 
instance: 
1) BöesEKEN, These Proc. 29th June 1912; 25th March 1916. 
2) BoURQUELOT, l.c. 
