On the germination of the tuber of the Jeru- 
salem Artichoke (Helianthus tuberosus). 
BY 
J. R, GREEN, M.A., B.Sc., 
Trinity College , Cambridge , 
Professor of Botany to the Pharmaceutical Society. 
GROUP of plants, prominent among the Compositae, 
JLjL store their carbohydrate reserve- materials in their 
tubers or tuberous roots in the form of inulin. Of these 
plants the dahlia ( Dahlia variabilis) and the Jerusalem arth 
choke ( Helianthus tuberosus) are most frequently met with. 
In the somewhat fleshy, though not tuberous, roots of the 
common species of Inula (/. Helenium and I. Conyza) a similar 
accumulation may be found. 
Inulin can be prepared from these plants by boiling the 
tubers, or roots, with large quantities of water, concentrating 
the decoction so obtained, and allowing it to stand till it de- 
posits a sediment. This is to be redissolved in a small quan- 
tity of hot water, decolourised by boiling with animal charcoal, 
and again concentrated, when it gradually deposits fairly pure 
inulin. This can be purified by redissolving and evaporating 
again till the inulin is precipitated, when it should be well 
washed with cold water containing a little alcohol. In the 
tuber the presence of inulin can be detected by soaking pieces 
in alcohol for two or three days and cutting sections. These, 
dipped in water and examined, show large sphaero-crystals 
of inulin deposited in the tissue, which often embrace several 
cells within their area. 
Inulin, prepared as described above, is a white powder which 
is readily soluble in warm water, dissolves only slightly in 
cold water, and is insoluble in alcohol. It is not thrown down 
[Annals of Botany, Vol. I. Nos. Ill and IV. February 1888.] 
