Referate. 43 
groups”. Both morphological comparison and breeding are necessary to 
create a Jordanon. 
The third term is Lotsy’s Species, defined as “a group of individuals 
of identical constitution, unable to form more than one kind of gametes’”. 
Besides morphological comparison and breeding an analysis by means of 
crossing is necessary to create a “species”, as we know that two morpho- 
logically alike organisms which by breeding give offspring like the parents, 
in some cases when crossed by one and the same other organism give 
different offspring. 
As hybrids he designates “all individuals able to produce more than 
one kind of gametes”, and as modifications “the non-transmittable effect 
of external circumstances”. 
I do not think that the choice of names for the three first categories 
is lucky, as I consider it both incorrect and inadequate to use the word 
“species” in Lotsy’s sense. It is better to let this word keep its old- 
fashioned meaning, synonymous with Lotsy’s linneon. This is in accordance 
with the historical development; and it would cause endless confusion, if, 
in every paper we read, we have to find out in which meaning the word 
species is used. We may, namely, be sure that systematists, plant-geo- 
graphers etc. will continue to use it in the old sense. We owe to the 
genetic researches the possibility of clearly defined terms, but even therefore 
we must create new names for them, and not restrict old names into special 
meanings. I propose to continue to use the term species instead 
of linneon and the term microspecies instead of Jordanon, and 
to place the term genospecies instead of Lotsy’s species. The 
word “genospecies” is created by Raunkiaer!) and defined as follows 
(translated from Danish): a genospecies is a form which by selffertilisation 
or fertilisation between individuals within the same “pure line” produces an 
offspring, genotypically alike and like the parent. I think this definition 
covers in all essentiai parts Lotsy’s definition of his “species”. If we admit 
the three terms: species, microspecies and genospecies, we avoid any con- 
fusion and remain in accordance with common practice. 
In the following I shall try to give an abstract of the main topics 
dealt with in Lotsy’s book. 
Variability (i. e. inheritable variability) upon which all the usual 
theories of evolution really are based, is, according to Lotsy, never proved 
and does not exist for the simple reason that genospecies do not vary. 
The only possibility for proving variability is to demonstrate that a homo- 
zygotic individual becomes heterozygotic without any crossing, or, in other 
words, a monogametic individual becomes polygametic. This is what we 
call mutation, but mutation must “for the present be discarded as a factor 
in evolution’’, as the classical object Oenothera Lamarckiana is not a genospecies, 
but “a mixture of heterozygotes of different constitutions throwing rogues 
(the pretended mutants) by a process of mendelian segregation’. (Also the 
theory of inheritance of acquired characters is not at all proved, and is in 
reality not different from the mutation theory, as mutation is inconceivable 
without some kind of inheritance of acquired characters). The only kind of 
mutants which, possibly, exist, are those arising from a loss of a factor; but 
1) In Salmonsen, Konversations Leksikon, 2 Udg., Bd. II (Köbenhavn, 
1915), p. 157. 
