TWENTY-THIRD ANNUAL MEETING. 101 



and various other agencies immediately or remotely under human control. 

 As it exists today, the flora of Michigan, in its varied wealth of grasses, 

 flowers, fruits, and trees, is one of the most beautiful alid productive 

 on the face of the earth. It becomes us to preserve where we can not 

 improve it, and to hand it down to the generations who succeed us, so far 

 retaining its original charm and freshness that they may still say, as we do, 

 in looking upon our birthright, " Si quceris jjen'tnsulam amcBnam 

 circumspicey 



DR. V. a VAUGHAN ON "THE FOOD VALUE OP FRUITS." 



When asked by my friend, Mr. ScoTT, to prepare a short paper to read 

 before you, I thought I would like to say a few words on the value of fruit 

 as food. It has appeared to me rather strange that, in this country where 

 we have such a variety of fruits, more stress has not been laid upon their 

 food value. I think that most people regard fruits as table luxuries which 

 we may enjoy, but without which we could live just as well as not and not 

 suffer any in health or vigor. That this view is not the correct one, I 

 hope to show in this short paper. I shall confine my remarks to the use 

 of fresh, ripe fruit, and shall not concern myself with the value of dried, 

 preserved, or canned fruit. In thus limiting my remarks, I do not wish it 

 to be understood that I do not appreciate the value of the last mentioned 

 articles of diet, but the limitation which I have placed ujjon this paper is 

 for the purpose of enabling me to bring out prominently a few points 

 which I consider of great importance. The most important constituents 

 of fresh fruit are the nitrogenous substances, the sugar, the organic acids, 

 and the inorganic salts. 



The chief nitrogenous substance is a vegetable albumen which is pres- 

 ent in small amount, and whose actual food value is not great, and we 

 will not take any time in discussing it. 



The per cent, of sugar varies in ripe fruits from about two in peaches 

 to as much as 17 or 18 in hothouse grapes. The origin of the sugar in 

 fruit is of interest and gives rise to a question which the scientist has not 

 fully answered yet. That it comes from the starch in some fruits is 

 unquestionably true; but other fruits, as grapes, contain no starch. It is 

 generally stated that in grapes the sugar, which increases remarkably in 

 amount during the process of ripening, is formed at the expense of the 

 organic acids, which are known to decrease in amount at the same time. 

 This very plausible explanation is, however, probably incorrect. During 

 the ripening process there is a marked increase in the amount of alkaline 

 base (potassium), and this, by neutralization, diminishes the quantity of 

 free organic acids, and thus the decrease in the acidity is accounted for 

 without resort to the supposition that the organic acids are converted into 

 the sugar. The increase in the sugar during ripening is most probably 

 due to an increased supply of this constituent from the juices of the vine 

 or tree. 



It has also been supposed that the after-ripening, which occurs in 

 apples and other fruits after they have been gathered, is due to an 

 increased formation of sugar. Certainly these fruits become sweeter by 

 the after- ripening process, but the researches of Portele and Marsh make 

 it highly probable that the increased sweetness is due to the slow conver- 

 sion of one sugar (dextrose) into another (lactose), the latter sugar being 

 sweeter than the former. 



