462 



THE POPULAR SCIENCE MONTHLY 



changes of animal chemistry. Taking for study the ripening of seeds 

 icith succulent coverings, the fruits the proper subject of this article 

 we may undertake to compare fruit-ripening with vegetable nutri- 

 tion on the one hand, and with animal nutrition on the other hand, as 

 follows : 



In Vegetable Nutrition. 



1. Oxygen is given to the 



air. 



2. Carbonic acid is taken 



from the air. 



3. The service of plant-green 



is required. 



4. Simple compounds are 



changed to those more 

 complex. 



5. The expended power of 



the sun is stored. 



6. Heat is absorbed. 



1. The changes represent re- 

 ductions and syntheses, 

 difficult to the chemist, 

 and hindered by atmos- 

 pheric conditions. 



8. Opposed to fermentations, 

 and to other changes 

 classed under the term 

 organic decomposition. 



In Fruit-Ripening. 



Oxygen is taken from the 

 air. 



Carbonic acid is given to 

 the air. 



The service of plant-green 

 is dismissed. 



Complex compounds are 

 changed to those more 

 simple. 



The stored-up power of the 

 sun is expended. 



Heat is liberated. 



The changes represent com- 

 bustions and dissocia- 

 tions, and are mostly 

 favored by atmospheric 

 conditions. 



The changes include a great 

 number of distinct fer- 

 mentations, some of 

 which are spontaneous 

 in the air, or occur in 

 cooking food. 



The important compounds of the vegetable kingdom 

 cellulose, starch, sugar, and many acids and other 

 products are common to the fruit and other parts 

 of the plant. 



In Animal Nutrition. 



Oxygen is taken from the 



air. 

 Carbonic acid is given to the 



air. 



Complex compounds are 

 changed to those more 

 simple. 



The stored-up power of the 

 sun is expended. 



Heat is liberated. 



The changes represent com- 

 bustions and dissocia- 

 tions, such as are fa- 

 vored by atmospheric 

 conditions. 



Some of the changes are al- 

 lied to fermentations, but 

 are mostly not liable to 

 occur without the living 

 body. 



Only a few animal products 

 are found in the vegeta- 

 ble kingdom. 



Fruit-ripening, then, coincides with vegetable nutrition in acting 

 with the same substances, and coincides with animal nutrition in 

 moving in the same direction. 



To inquire, now, somewhat in detail, into the more obvious of the 

 changes which constitute fruit-ripening, we may examine the propor- 

 tion and formation of the following five classes of Fruit-Products : 



1. Sugars (starches). 



2. Pectous substances and gums. 



3. Acids, tannin, and other glucosides. 



4. Ethers. 



5. Alkaloids. 



The analyses of fruits hitherto reported have mostly been made 

 by European chemists. The fullest reports of ripe fruits, upon which 

 I am in good part dependent, were made by Fresenius, from analyses 

 under his direction, nearly twenty years ago, and represent the fruits 

 of the Rhine district, obtained at Wiesbaden. 



1. Sugars. The prevailing sugar in fruits is glucose (dextrose), 



