148 CONSERVATIVE ORGANS. [LECT. IV. 



sidered as belonging to the latter merely from the 

 circumstance of their being underground produc- 

 tions. The older phytologists regarded them as 

 roots ; and we may still speak of them, without 

 much impropriety, as appendages to these organs, 

 if we obtain, in other respects, a correct idea of 

 their nature and functions. They assume a great 

 diversity of forms, which, as they frequently enter 

 into botanical descriptions, ought to be made fa- 

 miliar to the student. In describing them I shall 

 arrange the whole under two genera: a. Closely 

 attached tubers ; b. Filipendulous tubers. 



a. CLOSELY ATTACHED TUBERS are seated di- 

 rectly at the basis of the stem, or rather adhere 

 to it*, and grow in immediate contact with each 



" at every joint of which were produced new Potatoes ; at the 

 " lower joints there were three of these aerial Potatoes, one 

 " large, one the size of a pullet's egg, and a smaller one on each 

 " side of it. At the upper joints only one new aerial Potatoe 

 " adhered, and these became smaller the further they were 

 " removed from the root ; and, finally, at the summit there 

 " had been a flower, as there was now a seed-vessel, called a 

 " Potatoe-apple. All these new Potatoes at the joints of the 

 " stems were green, because they had not been etiolated by 

 " being secluded from the light, but the terrestrial roots 

 " (tubers) were white.'* Darwin's Phytologia, sect. xvii. 1 , 2. 

 * This place at the basis of the stem to which these tubers 

 usually adhere is marked by a little contraction or sometimes 

 protuberance, which the French botanists call le collet, the collar. 

 ' On donne aussi le nom de collet a une espece d'etranglement 

 " ou de rebord, qui separe une tige d'avec sa racine." Diet. 

 element, de Bot. par Buttiard. 



