68 OUR NATIVE ORCHIDS 



Another British cousin that Darwin experimented with 

 plainly shows by its actions that it fears that insect services 

 could not be relied on as completely as some thousands of 

 years gone by, for it has become adapted to fertilise itself. 

 The anther opens while the flower is in bud and pushes the 

 pollen partly out, and then, before there is the slightest 

 chance for an insect to come in, the pollen sends out long 

 tubes toward the stigma that penetrate its tissue and begin to 

 fertilise the ovules. Then the welcome to the insects is 

 extended, purely as a formal courtesy, it would appear, for 

 the pollen mass is balanced in such a way as though 

 it might fall at the slightest touch, exactly on its own 

 stigma. 



To Darwin, who was studying the orchids to prove the 

 theory of cross fertilisation against that of self fertilisation, this 

 orchid's vagary seemed a startling exception, especially when 

 he covered four blossoms with a net while they were still 

 in bud, and saw them open, and without the aid of any 

 insect produce capsules that looked as fine as any growing 

 free. But on weighing the seeds of the capsules of the covered 

 plants he found that they weighed more than one-third less 

 than those from an equal number of capsules on uncovered 

 plants. Moreover, under the microscope he discovered 

 that the self-fertilised capsules had seven times as many 

 bad seeds as those that were fertilised by the insects in the 

 garden, proving that cross fertilisation did take place, but 

 that the orchid had prepared itself for self fertilisation in an 

 emergency. 



