On the Occurrence of Mucin in Plants* 
BY 
J. Ishii, Nögakushi. 
In the animal as well as in the vegetable kingdom, there are 
found substances of slimy nature, which serve for different 
physiological functions; but while the slimes of animals belong 
to the protein compounds, all plant-slimes consist, so far as is 
yet known, of carbohydrates, corresponding either to the formula 
C 6 H I0 O 5 or C i2 H 22 O ii and yielding by hydrolysis different 
kinds of sugar; as, for instance, carrageen or the slime of an alga 
Chondrus crispas Lyngb) yields galactose ( Hädicke , Bauer and 
Tollens ), cerasin or the gum of the cherry-tree yields arabinose 
(Scheibler, Kiliani) , and the slime of beer-yeast yields mannose 
{Hessenland) . 
As a number of Japanese plants are so rich in slimy matters 
as to be applied on account of this quality for industrial pur¬ 
poses, I believed it to be, from a physiological as well as a technical 
point of view, of some interest to investigate their proper chemical 
relations. To my surprise I have found in the tuberous root of 
yams a slimy matter that is precipitated from its solution by dilute 
acetic acid. Further investigation has demonstrated beyond any 
doubt, that this slime belongs to the class of mucins , and as this 
remarkable occurrence is the first exception to a generally adopted 
rule, I will describe in the following lines my observations in detail. 
1. Short Description of Japanese Yams. 
There are two kinds of yams growing in this country, the 
one is called “ yamano-imo ” (Dioscorea japonica, Humb.) while the 
other is called “ jinenjo ” (Dioscorea batatas, Decaigne.) Both of 
them are found in a wild state and are very often cultivated. 
“ Naga-imo,” “ tsukune-imo ” and “ ichinen-imo ” are indeed the 
names given to the three different cultivated forms of “ jinenjo. ” 
All of these forms produce the large tuberous roots which are 
used as food. 
