JANUARY 5, 1912] 
farm crops in the College of Agriculture of 
Cornell University. 
Dr. H. Bassett, of the University of Liver- 
pool, has been appointed professor of chemis- 
try at University College, Reading. 
Dr. W. R. Boyce Gisson, lecturer in phi- 
losophy at the University of Liverpool, has 
been appointed professor of mental and moral 
philosophy at the University of Melbourne. 
DISCUSSION AND CORRESPONDENCE 
“ GENOTYPES,” “ BIOTYPES,” “ PURE LINES ” 
AND “ CLONES ” 
In a recent issue of Sctence* Dr. Jennings 
ealls attention to a double meaning which has 
been given to the word “ genotype” by several 
recent writers, myself among them, and points 
out the desirability of limiting the word to 
the meaning assigned to it by its originator, 
Dr. Johannsen. 
As one of the chief offenders, I wish to 
publicly repent my misuse of the term and to 
heartily join in the movement to limit the 
word “genotype” as used in the literature of 
genetics, to the fundamental hereditary con- 
stitution of an individual. The use of this 
word both for the hereditary constitution and 
for the group of individuals possessing an 
identical hereditary constitution, will lead to 
much confusion if continued. 
The word which Dr. Jennings says is much 
needed “for a concrete, visible group of or- 
ganisms ” “all with the same hereditary char- 
acteristics,” has been already supplied. In a 
symposium on the “Aspects of the Species 
Question” before the Botanical Society of 
America at Chicago, January 1, 1908, I 
pointed out*® the same need and expressed a 
hope that some one would “come forward 
with an acceptable short designation” for 
these “elementary forms” which had been 
classified by de Vries as “ elementary species ” 
and “varieties.” A few months later I dis- 
covered that my wish had been fulfilled before 
its utterance, by Dr. Johannsen, and his word 
“biotype” * was immediately adopted in my 
1 Science, December 15, 1911. 
2 Amer. Nat., XLII., 278, May, 1908. 
SCIENCE 27 
paper on “The Composition of a Field of 
Maize” * and made a part of the title of my 
work on “Bursa bursa-pastoris and Bursa 
Heegeri: Biotypes and Hybrids.”*° In view 
of these facts there was no excuse for my 
use of the word “genotype” in a taxonomic 
sense. 
Dr. Jennings also calls attention to an im- 
portant misuse of the expression “ pure line,” 
and here I must again admit a certain amount 
of guilt, as I was probably the first to include 
under this term groups of individuals related 
through the process of budding or any other 
method of vegetative reproduction. In 1904 
I wrote: 
By the ‘‘pure line’’ Johannsen means a series 
of individuals related only through the process 
of self-fertilization. On a priori grounds it seems 
proper to apply the term to every series of indi- 
viduals that do not combine elements of two or 
more ancestral lines through the equivalent of a 
sexual process. Thus, so far as hereditary quali- 
ties are concerned, there should be no reason to 
expect in a self-fertilizing population conditions 
different from those in a population related 
through budding or other method of vegetative 
reproduction, provided, of course, that the self- 
fertilizing population has not been so recently 
modified by a cross as to allow the analysis and 
recombination of characters derived from different 
ancestral lines. 
For this early departure from “the narrow 
path” I have in part atoned in my recent 
paper on the “Genotypes of Maize,”* by re- 
ferring to the vegetatively reproduced potato 
and paramecium as “clonal varieties,’ in 
contradistinction to the self-fertilizing “pure 
>This word was first proposed in 1905 in 
‘¢ Arvelighedslerens Elementer,’’ the Danish fore- 
runner of ‘‘Elemente der exakten Erblichkeits- 
lehre,’’ and was first used in English at the Third 
International Conference on Genetics in 1906. 
(See Report Third International Conference on 
Genetics, p. 98, 1906.) 
* Report American Breeders’ Association, IV., 
296-301, 1908. 
5 Carnegie Institution of Washington Publica- 
tion No. 112, 1909. 
° Torreya, V., 22, February, 1905. 
7 Amer. Nat., XLV., 234-252, April, 1911. 
