SPECIES 219 



nature of the case is such that it probably must always remain so. In 

 spite, however, of all these imperfections, steady and great progress has 

 been and is being made, and this natural system of classification must 

 be regarded as a most useful attempt to indicate just such genetic 

 relationships as exist among human beings. 



The divisions and sub-divisions thus established stand as follows: 



Divisions. — Of which there are two, the Cryptogamia and Phanero- 

 gamia, the latter being now often called Spermatophyfa, as the pro- 

 duction of seeds is regarded as their most important characteristic. 



Sub-divisions. — Leaving out of consideration the divisions of the 

 Cryptogamia, we find the Phanerogamia divided with two sub-divisions, 

 the Gyvinospermae and the Angiospermae, the latter the higher. 



Classes. — Leaving out of account the Gymnospermae, the Angio- 

 spermae are divided into two classes, the Monocotyledons and the 

 Dicotyledo7is. 



Series. — The Dicotyledons are divided into three series, the Thal- 

 amiflorae, Disciflorae and Calyciflorae. 



Cohorts. — Each of the series named above is divided into a number of 

 Cohorts, or orders. Thus the Thalamiflorae have 6 cohorts, namely, 

 Rdnales, Parietales, Polygalinae, Caryophyllineae, Guttiferales, and 

 Malvales. 



Families. — Each cohort consists of a number of Families, of which 

 there are about 300 among flowering plants, the Ranunculaceae or 

 Buttercup Family and the Compositae or Daisy Family being examples. 



Sub-families and Tribes. — Families, if large or heterogeneous, are 

 often divided into Tribes, or into Suk-families, the latter then divided 

 into Tribes. Thus, the Ranunculaceae contain 5, the Compositae 13 

 tribes. 



Genera. — Families, either directly or through their tribes, are divided 

 into genera, of which the most modern authorities recognize between 

 8000 and 9000 in all the families of flowering plants. The genera are 

 very irregularly distributed among the families. Thus, the family 

 Columelliaceae contains but one genus, Columellia, while the Compositae 

 is made up of some 800 of them. 



Species. — Genera, either directly or through a number of Sub-genera, 

 are made up of species, of which there are probably not far from 250,000 

 now described among flowering plants. These are very irregularly 

 distributed among the genera, many of the latter containing but one 

 species, while others contain hundreds. Solanum, probably the largest 

 genus, has been credited with as many as 1200 species. 



