wonderful resources when they are needed to maintain 

 the life of species, and the tuber is probably a means 

 which the potato plant instinctively, as it were, called 

 to its aid to help it hold its place in the vegetable 

 world. 



The Formation of Tubers. 



The most striking feature in connection with the 

 tuber is, that although formed underground it is not a 

 portion of the root, but is a portion of an underground 

 stem. The seed of the potato is contained in fruits 

 borne on the stem or branches above-ground. Even 

 those solanaceous plants which develop tubers retain 

 the faculty of producing seed, unless the conditions 

 under which they are grown are persistently antago- 

 nistic to seed production. This happens when all efforts 

 are diverted towards the development of tubers, in con- 

 sequence of treatment strongly opposed to the growth 

 of the plant under natural conditions. The tuber, 

 although frequently called seed, and to which reference 

 is made when speaking of " seed potatoes," is not a 

 seed in the true sense ; nor is it a root, or a portion of 

 root, as in the case of the carrot. A tuber is an 

 enlarged portion of an underground stem, several of 

 which are usually formed on one plant. It is not until 

 the plant has made considerable growth that these 

 stems attain appreciable size. As the plant approaches 

 to maturity they grow rapidly, and may be easily dis- 

 tinguished from the true roots, as they are usually 

 thicker, whiter, and free from rootlets. If the extreme 

 tip of these branches is examined it is seen that there 



