(374) 
may associate with it certain of the older species that seem to 
him out of place in their former alliance. As the years go 
by other species are discovered and added to this genus until 
it becomes cumbersome, when some other student decides 
to divide it. He lops off groups of species here and there, 
giving them new generic names. It has very often happened 
that the original species or group of species is thus taken out 
of the genus and renamed while the old name remains with 
a group that was entirely unknown to its author. Any at- 
tempt in later years to restore this name to its original, proper 
application must involve a most confusing shifting of generic 
names. This manner of dividing genera has come to be 
called the ‘‘method of residues.” It is responsible for a 
large part of the confusion which exists in the use of generic 
names at the present time. The process has been carried so 
far that in some cases all of the recognizable species have 
been taken away from a genus, leaving only a mass of doubt- 
ful or unknown sfeczes inguirendae under the old name. 
The case of Sphaerta may be cited as an example. The 
more advanced thinkers among the taxonomists have become 
convinced that the only method for preventing this most un- 
fortunate shifting of names is to insist that a generic name 
shall always be retained for the species or group of species 
to which it was first applied, or in other words, that a generic 
name to be valid must always be inseparably associated with 
some type species. ‘This is, in reality, only the strict recog- 
nition of the law of priority, but it is known as the ‘‘ method 
of types.” Unfortunately this principle has not been widely 
accepted in Europe and it was voted down at the recent In- 
ternational Botanical Congress held in Vienna during the 
summer of 1905. It is, however, recognized by the great 
majority of American systematists and has been incorporated 
in the code of botanical nomenclature formulated by the 
nomenclature commission appointed by the Botanical Club 
of the American Association for the Advancement of Science 
at its Washington meeting, January 2,1903. This code was 
published in the Bulletin of the Torrey Botanical Club, May, 
