74 PLANT HYBRIDIZATION BEFORE MENDEL 



Royal Botanical Garden, upon a mastic tree {Pistacia lentiscus), 

 and on a terebinth {Pistacia terebinthus), both of which were suc- 

 cessful, especially so in the case of the latter, from which he was 

 able to collect nearly half a "Metze" — nearly two liters — of seed. 

 After the two experiments mentioned, Gleditsch remarks that 

 he allowed the palm to remain eighteen years, without securing 

 another fertilization, not, however, without having taken much 

 pains to procure pollen from other places. At the end of the 

 time referred to, he addressed himself to Kolreuter, who was at 

 the time medical adviser to the Margrave of Bade-Bourlach, and 

 to whom he refers as : 



"One of the most diligent naturalists of our times, who sent me, in the 

 month of May, some of this powder of the flowers, which I had searched 

 for since so long in vain, with a little quantity of the same powder which 

 he had already kept for a year." (p. 9.) 



The latter, he states, had no fertilizing effect, but the former 

 was entirely effective. The details of the experiment are not un- 

 interesting. The palm put out successively eleven clusters of 

 flowers between the ninth and twenty-sixth of May. The tree was 

 thoroughly rid of all debris and of all clusters of dried flowers. 

 On account of the height of the tree, it was necessary to erect a 

 scaffold around its crown, so that the flowers could be readily 

 pollinated, and subsequently be observed as long as necessary. Of 

 the eleven flower clusters, three were chosen for pollination, which 

 were the nearest to the glass of the greenhouse and hence the 

 m.ost exposed to the sun. 



One of these, the smallest, was pollinated with the pollen which 

 had been kept for a year, "but," he says, "it did not produce any 

 effect, as I was able from the first to observe at the end of fifteen 

 days." (p. 10.) The second and third clusters were pollinated with 

 the fresh pollen. 



"Having been obliged to keep for eight days the fertilizing powder 

 which had been sent me from Carlsruhe, I proceeded to the second fe- 

 cundation, in the manner which I have already related, in the last days 

 of the month of May." (p. 10.) 



"when I afterwards examined," he continues, "what had been the effect 

 of the powder on the flowers, I found that the edge of the flower with 

 the blunt anthers had fallen, or at least had suffered some change, the 

 little ovaries had become softened, had taken on a little growth, their 

 color had become modified, and they had become brilliant." (p. 11.) 



In his first two pollination experiments with this tree, Gleditsch 



