PLANT HYBRIDIZATION BEFORE MENDEL 43 



the two natural species, but that with them especially also all the parts 

 belonging to the flower, the anthers alone excepted, taken in comparison 

 with those of the two natural plants, showed an almost geometrical pro- 

 portion." {ib., pp. 30-1.) 



The anthers of the hybrid Nicotiana contained less pollen than 

 those of the parents, and instead of having their regular elliptical 

 form 



"they were in comparison quite irregular, shrivelled as though rubbed to 

 pieces ; they contained almost nothing of a fluid material, and were, in 

 a word, simply empty husks." {ib., p. 31.) 



Kolreuter then goes on to say : 



"The fertility of this new plant appeared to me, therefore, extremely 

 questionable, and the results confirmed my suspicion completely ; for 

 among the almost innumerable quantity of flowers there was not one 

 to be found which had borne even a single seed, even though they had 

 been immediately covered with a large quantity of their own pollen 

 dust ; while on the other hand, with the two natural species, every 

 capsule is accustomed to bear four or five hundred seeds. This plant 

 is thus in the real sense a true, and, so far as it is known to me, the 

 first botanical mule which has been produced by art." {ib., p. 31.) 



In this connection Kolreuter refers as follows to the supposed 

 hybrid Tragopogon^ reported by Linnaeus to the Imperial Acad- 

 emy of Sciences at St. Petersburg, and which bloomed in the bo- 

 tanical garden at St. Petersburg in the spring of 1761, as being 

 in his expression "only half a hybrid." 



"For the hybrid goat's-beard, which the celebrated Linnaeus considers 

 in his new prize essay, is not a hybrid plant in the real sense, but at 

 most only a half hybrid, and indeed in different degrees, as I will clearly 

 and plainly demonstrate at another opportunity, with many reasons 

 which appear in part from the nature and peculiarity of the composite 

 flowers, and from certain experiments instituted upon the time of fer- 

 tilization of the same ; in part from the structure of the above-mentioned 

 presumed hybrid itself, which had been raised by me from seeds which 

 Linnaeus had sent, together with his prize essay, to the Honorable Rus- 

 sian Imperial Academe' of Sciences, and which have bloomed the past 

 spring in the Academy's garden at St. Petersburg." {ib., p. 32.) 



The hybrid Nicotiana paniculata -.X rustica obtained by Kdl- 

 reuter, he pollinated, in part with the pollen of paniculata and in 

 part with that of rustica^ and obtained fertile seeds in both cases, 

 but in lesser numbers than with the self-fertilized parents. Kol- 

 reuter's conceptions regarding hybrid fertilization, and the pro- 

 duction of what he refers to as a half hybrid appear in the next 

 following pages. His conception is that from any plant, from 



