INTERNATIONAL RULES OF BOTANICAL NOMENCLATURE. 81 
“The principles (Art. 1-9, 10-14 and 15 - 18) are the foun- 
dation of the rules and recommendations. The rules (Art. 10 — 58) 
destined to put in order the nomenclature which the past has 
bequeathed to us, and to form the basis for the future, are always 
retroactive: names or forms of nomenclature which are contrary 
to a rule cannot be maintained. Recommendations bear on 
secondary points, their object being to ensure for the future a 
greater uniformity and clearness in nomenclature: names or forms 
of nomenclature contrary to a recommendation are not a model 
to copy, but cannot be rejected.” 
Article 9. “The rules and recommendations of botanical nomen- 
clature apply to all classes of the plant kingdom, reserving special 
arrangements for fossil plants and non-vascular plants.”? 
Article 14. “‘The fertilization of one species by another, gives rise 
to a hybrid (hybrida); that of a modification or subdivision of a 
species by another modification of the same species gives rise to a 
half-breed (mistus, mule of florists). 
Recommendations—1. The arrangement of species in a genus or 
in a subdivision of a genus is made by means of typographic signs, 
letters or numerals. Hybrids are arranged after one of the parent 
species, with the sign x placed before the generic name. 
The arrangement of subspecies under a species is made by letters 
or numerals; that of varieties by the series of Greek letters a, /, y, 
etc. Groups below varieties and also half-breeds are indicated by 
letters, numerals or typographic signs at the author’s will.” 
Article 19. ‘‘Botanical nomenclature begins with the Species 
Plantarum of Linneus, ed. 1 (1753) for all groups of vascular 
plants. It is agreed to associate genera, the names of which 
appear in this work, with the descriptions given of them in the 
Genera Plantarum ed. 5 (1754).” 
1 These special arrangements have been reserved for the Congress of 
1910. They comprise: 1. Rules bearing on special points in relation to 
the nature of fossils or the lower plants; 2. Lists of nomina conservanda 
for all divisions of plants other than Phanerogams. 
F—Sept. 5, 1906, 
