176 ACADEMIC BOTANY. 



of which the Peas have 11, the Logwoods 7, the Mi- 

 mosas 3. 



426. Varieties, Races. — If we plant two peas from the 

 same pod, or two seeds from tiie same apple, in diiferent 

 soils and climates, giving to each a diiferent course of treat- 

 ment, we produce Varieties, such as the different sorts of 

 cultivated Peas and Apples. In many cases these Varieties 

 persist under cultivation, thus establishing Races; though 

 both races and varieties are apt to revert to the original 

 type if left to run wild. Our cultivated Wheat is a per- 

 sistent race from the Wild Wheat {.iEgilops ovaia) which 

 abounds in Southern Europe, Sicily, and Asia Minor. 



427. Galen (a.d. 130-200) states that his father and himself had 

 observed that Wheat degenerates into ^gilops ; but this statement led 

 to no inquiry until M. Esprit Fabre, of Agde, Prance, proved the fact. 

 In 1839 M. Fabre sowed the seeds of .Mgilops tritieoides, — a form of 

 A. ovaia, — and after twelve years of industrious experiments he ob- 

 tained cultivated Wheat as we now have it. 



428. Hybrids are made by cross-breeding; that is, by 

 applying the pollen from one flower to the pistil of another 

 flower of a different Species, but in the same Genus. The 

 Azaleas hybridize freely; so do the Pelargoniums. But 

 nature does not like cross-breeding ; it rarely occurs among 

 wild flowers, and hybrids usually produce no seeds. Natu- 

 ral species, therefore, should be examined for classification ; 

 Varieties, Races, and Hybrids, though valuable to the 

 gardener and florist, are worth nothing to the botanist. 



429. Scale of Classification. — In classifying plants Jus- 

 sieu begins with the lowest or simplest and ascends to the 

 highest or most complex. De CandoUe (1778-1841) 

 adopted Jussieu's method, but reversed it ; he begins with 

 the highest and descends to the lowest. De Candolle's 

 method was adopted in England and America ; most of 

 the class-books published in this country thirty years ago 

 — many of which are still used in the schools — are based 

 upon it. But this was as great a mistake as it would be 

 to put a student to the solution of Euclid's 47th Propo- 

 sition before teaching him the Multiplication Table; and 

 the rapid advance made in the science of education has re- 

 sulted in the universal adoption of the inductive method of 



