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to reckon priority, or in case two or three dates have been mentioned 
one has been taken for genera, another for species, and perhaps a 
third for families and higher groups. The lack of practical success 
of the proposed reforms has, it is believed, been in part due to a 
failure to perceive that the historical development of botanical classi- 
fication has been such that no single date can be taken for all groups 
of plants without causing much needless change and uncertainty in 
the resulting nomenclature. For example, although the year 1753 
seems eminently desirable as the starting point for the nomenclature 
of the spermatophytes, the use of this date among the lower groups, 
as for instance the Algae, appears not only highly inexpedient but 
well-nigh farcical. Among the flowering plants both genera and 
species had by 1753 been interpreted with a tolerable degree of 
definiteness, and their descriptions were at that time drawn with 
sufficient understanding of morphology and diagnostic features to 
make them in general intelligible to future generations. On the other 
hand, at the date of Linnaeus’s Species Plantarum the knowledge of 
the Algae was far too crude to form a satisfactory basis for their 
classification or nomenclature. Even the optical appliances necessary 
for the intelligent examination of this group had not been invented. 
What is here said of the Algae is quite as true of the fungi and 
applies in lesser degree even to the bryophytes and pteridophytes. 
Furthermore, the great difficulty or impossibility of preserving 
specimens in several of the lower groups, and the consequent fact 
that no type specimens are now extant for a large proportion of the 
species of the lower orders, render it all the more imperative that 
the beginning of nomenclature in these groups should not be carried 
back to a time of brief, vague and unintelligent descriptions. 
In consideration of these facts it seems desirable that in the 
nomenclature of the spermatophytes priority should be reckoned 
from the publication of Linnaeus’s Species Plantarum in 1753, but 
in the case of all other groups, from a date near 1800, to be more 
exactly determined by a committee of specialists in cryptogamie 
botany, appointed by the International Congress in whatever manner 
it may seem best. 
As the nomenclature of cryptogamie botany involves other diffi- 
culties which are largely peculiar to itself, such as the confusion 
caused by the different naming of alternating generations, the 
important question of publication by issue in exsiccatae, the vague 
