REPORT OF THE CONFERENCE ON GENETICS, 89 
The same “law ’’—.e. the same ratio of results—obtains also with 
other pairs of simple characters and with other plants (or animals), always 
premising that the original parents which you cross-fertilise are them- 
selves pure strains, in respect of each of the different characters under 
consideration, and that after the first cross the resulting plants are self- 
fertilised in future (inbred in animals), and not re-crossed with a third 
strain—which obviously would bring in very difficult and altering com- 
plications. 
This law of inheritance is by no means all that Mendel discovered, 
but it is the basis and foundation from which he pursued his further 
investigations, and which has enabled modern biological students to feel 
that their work rests on no mere theory, however ingenious or plausible, 
but on the unshakable premiss of undoubted natural law. 
Translation of Mendel’s letter to Carl Négeli. 
Dear Sir,—Accept my most hearty thanks for the Hieraciuwm seeds 
safely received. I feel very grateful to you for this kind gift, and I highly 
appreciate your generous intention to send me living plants also. I shall 
make every endeavour to raise the various possible hybrid forms between 
these species, and if they prove fertile their posterity shall be studied for 
several generations. 
It was with great regret that I received the news of your accident on 
March 1, and I heartily rejoice that it was not followed by very serious 
consequences. 
A complete and most unexpected change has lately come to pass in 
my circumstances. My unworthy self was chosen on March 30 by the 
Chapter of the institution to which I belong to be its head for life. From 
my hitherto humble position as a teacher of experimental physics, I thus 
find myself suddenly translated into a sphere where everything is so 
strange that it will be only after much time and effort that I shall be able 
to feel myself at home. This, however, shall not prevent me from 
continuing the experiments in hybridisation which have now become so 
dear to me, and I even hope when I have got used to my new position to 
be able to devote more time and attention to them. 
In my experimental plot the plants have got through the winter well 
on the whole, and they are now fairly forward ; most of the Piloselloidea and 
the Archieracia are already showing their flower-buds. So far the following 
crosses can be seen to have succeeded:—H. Awricula x H. Pilosella, 
H. prealtum (Bauhini) x H. aurantiacum, and probably H. Pilosella 
x H. Auricula. Of the autumn seedlings of the hybrid H. prealtwm 
x H. stoloniferwm (Autor) which was raised last year, about 100 have 
overwintered. Thus far these plants (still of course small) in both the 
structure and the hairyness of the leaves are indistingwishable from each 
other and agree with the hybrid mother-plant. I look forward to their 
further development with some eagerness. 
Your devoted friend, 
GREGOR MENDEL, 
Abt und Prélat des Stiftes St. Thomas. 
Briinn, May 4, 1868. 
