S U M M .'\ R YLJndifferentiiited and differentiated tissues ot" Dcudrobitim exhibited no difference in their preference for sugars. The uptake of sugars was more rapid by undifferentiated tissue. I-'ructose provided the best carbon source for botli tissues. Sucrose was hydrolysed before it was taken up, as the result of invertase acti\ ity. Both acid and alkaline invertase were present and invertase activity was detected in the soluble and cell wall traction. There was a gratlual increase in invertase activity of tissues grown in sucrose-containing medium with time but not in tissues grown in fructose-containing medium.