Ch. n.]l ORCHIDS. 45 



During the same year I published in the Journal of the 

 Linnean Society, a paper On the Two Forms, or Dimorphic Con- 

 dition of Primula, and during the next five years, five other 

 papers on dimorphic and trimorphic plants. I do not think 

 anything in my scientific life has given me so much satisfaction 

 as making out the meaning of the structure of these plants. I 

 had noticed in 1838 or 1839 the dimorphism of Linum fiavum, 

 and had at first thought that it was merely a case of unmeaning 

 variability. But on examining the common species of Primula, 

 I found that the two forms were much too regular and constant 

 to be thus viewed. I therefore became almost convinced that 

 the common cowslip and primrose were on the high-road to 

 become dioecious ; — that the short pistil in the one form, and 

 the short stamens in the other form were tending towards 

 abortion. The plants were therefore subjected under this 

 point of view to trial ; but as soon as the flowers with short 

 pistils fertilised with pollen from the short stamens, were found 

 to yield more seeds than any other of the four possible unions, 

 the abortion-theory was knocked on the head. After some 

 additional experiment, it became evident that the two forms, 

 though both were perfect hermaphrodites, bore almost tho same 

 relation to one another as do the two sexes of an ordinary 

 animal. With Lythrum we have the still more wonderful 

 case of three forms standing in a similar relation to one 

 another. I afterwards found that the offspring from the union 

 of two plants belonging to the same forms presented a close 

 and curious analogy with hybrids from the union of two 

 distinct species. 



In the autumn of 1864 I finished a long paper on Climbing 

 Plants, and sent it to the Linnean Society. The writing of 

 this paper cost me four months : but I was so unwell when I 

 received the proof-sheets that I was forced to leave them very 

 badly and often obscurely expressed. The paper was little 

 noticed, but when in 1875 it was corrected and published as a 

 separate book it sold well. I was led to take up this subject 

 by reading a short paper by Asa Gray, published in 1858. He 

 sent me seeds, and on raising some plants I was so much 

 fascinated and perplexed by the revolving movements of the 

 tendrils and stems, which movements are really very simple, 

 though appearing at first sight very complex, that I procured 

 various other kinds of climbing plants, and studied the whole 

 subject. I was all the more attracted to it, from not being at 

 all satisfied with the explanation which Henslow gave us in his 

 lectures, about twining plants, namely, that they had a natural 

 tendency to grow up in a spire. This explanation proved quite 



