44 PLANT HYBRIDIZATION BEFORE MENDEL 



which, through fertilization with another, a complete hybrid 

 can be produced, a mere "tincture," as it were, may likewise be 

 transmitted, in the proportion in which its own pollen stands to 

 that of the other that is also purporting to function as the male 

 parent in the fertilization process. This "tincture," or supposed 

 partial contribution of the female parent, through the agency of 

 its own pollen, is presumed by Kolreuter to be (p. 34) the cause 

 of the production of "half-hybrids." This conception of the effect 

 of the pollen as a mass-effect, brought about through the secretion 

 of fertilizing substance by the pollen grains, which was the 

 more effective the greater the quantity of it, was the prevailing 

 theory for some time after Kolreuter's day. Kolreuter's first 

 "Vorlaufige Nachricht" closes with a brief discussion of six ex- 

 periments which he conducted with regard to nectar-producing 

 plants (pp. 34-7), and which need not be referred to here. 



The first "Fortsetzung" to the preceding appeared in 1763. 

 The "Vorlaufige Nachricht" was dated September 1, 1761, the 

 place of publication not appearing. The first "Fortsetzung" is 

 dated at Calw, December 10, 1762. At this time Kolreuter 

 appears in the publication as Professor of Natural History at 

 Wiirtemberg. The preface opens with Kolreuter's expression of 

 conviction, that from the experiments in the preceding report the 

 sex of plants was most completely proved, as well as the theory 

 that reproduction in plants resulted from the production of two 

 kinds of fertilizing material. The "Fortsetzung" therefore begins 

 with the statement : 



"To the production of every natural plant two similar fluid materials 

 of different sort are demanded. The one of these is the male, the other 

 the female." 



Since these materials are of different sort, or are different from 

 each other in their nature, it is therefore easy to understand that 

 the force or strength of the one must be different from that of 

 the other. 



"From the union and commingling of these two materials, which oc- 

 curs most intimately and in an orderly manner according to a definite 

 relationship, there arises another of an intermediate sort, and which 

 consequently also possesses an intermediate composite force, arisen from 

 those two simple forces, just as through the union of an acid and an 

 alkaline substance a third or intermediate salt originates." (p. 42.) 



It is worthy of mention that Kolreuter records, regarding his 



