IOWA ACADEMY OF SCIENCES. 
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from 1695 to 1728, or from Tournefort to Micheli. The 
third period covers the time from 1729, in which appeared 
Micheli’s “Nova Plantarum Genera juxta Tournefortii 
Methodum Disposita”, in which attention is called for the 
first time to the impropriety of grouping all lichens under 
the single genus, Lichen , to 1779, or to Weber, whose name 
also seems to appear as Wigger. Period four reaches from 
1780, in which year Weber in his “Primitiae Florae 
Holsatiae” (the author’s name appearing as Wigger) sue*- 
cessfully departed from the old custom of classifying lich- 
ens entirely according to the general form and structure of 
the thallus and considered also the apothecia, to 1802, or 
to Acharius. The fifth of Kremplehuber’s periods extends 
from 1803, in which year Acharius, in his “Methodus Lich- 
enum”,for the first time gave somewhat adequate descrip- 
tions of all known lichens, to 1845 or to DeNotaris. Krempel- 
huber’s sixth and last period extends from 1846, when ap- 
peared De Notaris’ “Frammenti Lichenographici”, in which 
for the first time some prominence is given to spore char- 
acters in the classification of lichens, to 1870, in which 
year Krempelhuber completed his history in the third 
volume of his “Geschichte.” Schneider in his recent “Text- 
book of Lichenology”, presents a somewhat different divis- 
ion into periods, which is as a whole scarcely an improve- 
ment upon Krempelhuber’s method of division. However, 
we may well agree with Schneider that the announcement 
by Schwendener of his belief in the dual nature of lichens 
in 1868 may be regarded as the beginning of a new period, 
the importance of this announcement hardly appearing 
before Krempelhuber had completed his work. Schneider 
also recognizes another period beginning with the year 
1894, when appeared Reinke’s “Die Svellung der Flechten 
in Pflanzensystem”, in which the author put forth his 
views regarding the autonomous nature of lichens and the 
consequent propriety of still regarding them as a distinct 
class of plants. This is by no means Reinke’s only contri- 
bution to lichenology, and no one who has seen his papers 
can doubt their great value. However, there is as yet no 
great evidence that his peculiar views as to the autonomy 
