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for example, the Magnoliaceae, which are 
said to be analagous in this respect to many 
animal groups — can be attributed only to the 
lowering of temperatures in the northern re- 
gions during the time of glaciation. 
CONCLUSION 
These investigations have offered statistical 
evidence that the phylogenetically older types 
of about 10 large taxonomic groups of the 
higher plants are found, either exclusively or 
in their great majority, in Australia. By anal- 
yzing the floras of the lands near Australia 
today, and by drawing analogies from the 
floras of the southern parts of all of the other 
continents, it can be concluded that the an- 
cestors of the Australian plants must have 
existed in Australia during the times of the 
Upper Cretaceous period. This can be the 
only conclusion because it would be impossi- 
ble for the Australian flora to form one vast 
atavism, if only because atavisms are rare, 
when they are encountered at all, and usually 
play no part in the formation of species. 
It should be stressed that in order to reach 
this conclusion no contrived assumptions 
were made regarding the primitiveness of the 
characteristics of the Australian plants: Con- 
cepts and judgments of primitiveness were 
based entirely upon the well-established cri- 
teria of the older taxonomic systems (the 
Naturliche Pflanzenfamilien of Engler and 
Prantl, for example) and upon the general 
discussions of phylogenetically important 
characteristics given by Wettstein in his hand- 
book of systematic botany (1935) and by 
myself ( Suessenguth, 1938), without de- 
pendence upon rules or criteria established 
particularly for the Australian flora. The spe- 
cial questions of the phylogenetic age of 
Australian families put in this paper, and the 
answers proposed to them, have not been 
presented before, to my knowledge. 
The data obtained in these investigations 
would suggest that natural immigrations of 
plants into Australia, after the beginning of 
its isolation from Malaysia, were not very 
likely — or at least were not very plentiful — 
the enormous degree of endemism which 
Australia now exhibits being evidence against 
any considerable change in later times. 
It cannot be established with certainty 
whether or not the plants of the primitive 
genera of the 10 major Australian families 
are not only endemic by preservation but are 
also plants which have originated in Aus- 
tralia and which have existed there since their 
beginning to become the ancestors from 
which the families have spread throughout 
the world. In the majority of cases I do not 
think it likely that these plants have been 
disseminated from an Australian center in- 
asmuch as paleontological evidence concern- 
ing animals shows that many animals which 
at one time were widely distributed have 
been preserved alive in Australia while they 
have become extinct in other regions. Obvi- 
ously, what has happened to animals could 
also have happened to plants. 
We can conclude, however, from the in- 
direct evidence presented by the Australian 
flora that the development of primitive fam- 
ilies of the angiosperms must have taken 
place during the Middle and Lower Cretace- 
ous period or, possibly even earlier, during 
the Jurassic period. But this conclusion, while 
it is supported by the endemic nature of the 
Australian flora — which, of course, was iso- 
lated when the connection of Australia with 
Malaysia was ended in the Upper Cretaceous 
period — has yet to be confirmed by the dis- 
covery of fossil evidences of angiosperms in 
formations of those Middle Mesozoic times. 
REFERENCES 
Behrmann, W. 1937. [No title supplied.] 
Frankfurter Geog. Hefte, Jahrg. 1 1 : 19-20. 
Briquet, L 1897. Labiatae. In: Engler and 
PrantEs Naturliche Pflanzenfamilien . IV 
Teil, Abt. 3a: 183-375. Verlag W. Engel- 
mann, Leipzig. 
