4 
species is less to be expected partly for the reason that the region of 
growth of marine algae, pelagic species excepted, is more limited than 
that of land plants. But even in algae, it is probable that the known 
species will be considerably increased. 
The fungi offer a better field for comparison than other groups. 
It is certainly true that the number of described species is decidedly 
smaller than that of phaenogams. Are we then to conclude that there 
are fewer fungi in the world than there are phaenogams? By no 
means, for there is a possible inference which may be drawn from a 
knowledge of the distribution of fungi to which, it seems to me, great 
weight should be given. Year by year the number of known parasitic 
fungi goes on increasing and, although we cannot assume that probably 
every phaenogam has its parasite, the proportion which have is con- 
stantly increasing. We also know that some species have not only one 
but many parasites and, as a rule, the species which from their economic 
value have been most carefully studied are the hosts of many fungi. 
As an instance I may mention the species of the genus Vitis on which 
several hundred species of fungi are known to grow, some to be sure 
found also on other plants, but a large number peculiar to this 
genus. When all genera have been studied as carefully as Vitis, we 
shall undoubtedly find that the number of parasitic fungi in existence 
is enormous. If to the parasitic we add the thousands of saprophytic 
fungi, it may well be asked whether eventually it will not prove to be 
true that the number of species of fungi is as great as that of phaeno- 
gams. It seems to me that it should be plain to every one that if in the 
Species Plantarum the proportion of phaenogams to cryptogams is 
about ten to one, we must admit that although the work is sufficiently 
comprehensive to serve as a basis for the nomenclature of the former, 
it is entirely inadequate in the case of the latter. 
I have referred to the restricted range of the species of cryptogams 
described by Linnaeus and to their small number. If we go farther 
and examine the character of the descriptions themselves we find that 
they are in many cases vague and unintelligible, which is nothing more 
than might have been expected in that day before the scientific study 
of the group had really begun. The algae in particular are from the 
modern point of view a strange medley. The genera Jungermannia, 
Targionia, Marchantia, Blasia, Riccia and Anthoceros I have in my 
