I'JG TWENTY-FIRST REPORT. 



medicinal constituents there are usually a number of bitter and even acrid 

 substances which are destroj'ed by the cold of winter. Among the root-yielding 

 drug plants which we have grown at the University of Michigan are bella- 

 donna, marshmallow, poke and inula. The yield of each of these from 

 first year plants would be from 500 pounds to 1.000 pounds. 



CUKING AND FERMENTATION. 



Recent investigation of drug constituents seems to show that the quality 

 can be improved by subjecting them to a sweating or curing process. During 

 this operation certain aromas are developed which enhance their value. This 

 is probably best seen in the curing of tobacco where we begin with a leaf that 

 has neither flavor nor aroma but develops a final product that is fit for the 

 enjoyment of the gods. The value of tobacco depends not so much upon the 

 nicotine content as upon the generation of minute quantities of those con- 

 stituents which give it its particular flavor and aroma. Of course, in the 

 curing of tobacco there are other qualities which must be developed as that 

 of burning or proper combustion. 



xipart from climate and soil there are three prime factors which underly 

 the curing of tobacco, namely, heat, moisture and light. Of course there 

 must be proper ventilation and the time element is an important one. It was 

 with the view of studying these fundamental changes that a considerable 

 number of Havana and Pennsylvania tobacco plants were grown at the 

 University Gardens. The results thus far would seem to indicate that tobacco 

 may be made a valuable product in this vicinity and acre yielding at least 

 40,000 large leaves. 



In quite a number of medicinal plants the poisonous constituent is gen- 

 erated by .what is known as a mother substance. The latter is broken down 

 in the process of curing, thus generating a number of important principles. 

 This is well illustrated in the curing of vanilla, where the odorous principle 

 known as vanillin is produced during the fermentation. A number of years 

 ago, Mr. Knox, a student in the College of Pharmacy, Univer.sity of Michigan, 

 showed that in cola the caffiene was produced in a similar way from a mother 

 substance. It is quite likely that in belladonna, digitalis and a number of 

 other plants a slow drying will enhance the value of the leaves. In other 

 words, if the leaves are first allowed to wilt, preferably in the shade and to 

 some extent allowed to sweat, care being taken that the temperature does not 

 get too high, it is likely that superior drugs will be produced. This is one of 

 the most valuable results of our work at the garden- during the past summer. 



One of the most interesting plants that we had under cultivation during 

 the past summer was rhubarb. The plant yielding this drug resembles the 

 garden rhubarb Imt produces large fleshy rhizoiues which it seems quite likely 

 will (»verwin!or. I had similar plants growing in large packing boxes placed 

 on a roof when I was conducting experiments in Pliiladelphia. These lived 



