294 BOTANY [Chap. X 



Letter 620 the opposite side of the flower. Hence the suspicion has 

 crossed me that if many plants of the Heterocentron roseum 

 were examined, half would be found with the pistil nearly- 

 upright, instead of being rectangularly bent down, as shown 

 in the diagram ; * or, if the position of pistil is fixed, that in 

 half the plants the petal-facing stamens would bend down, and 

 in the other half of the plants the sepal-facing stamens would 

 bend down as in the diagram. I suspect the former case, as in 

 Centradenia I find the pistil nearly straight. Can you tell me? 2 

 Can the name Heterocentron have any reference to such diver- 

 sity ? Would it be asking too great a favour to ask you to 

 look at dried specimens of Heterocentron roseum (which would 

 be best), or of Monochcetum, or any eight-stamened Melasto- 

 mad, of which you have specimens from several localities (as 

 this would ensure specimens having been taken from distinct 

 plants), and observe whether the pistil bends differently or 

 stamens differently in different plants ? You will at once 

 see that, if such were the fact, it would be a new form of 

 dimorphism, and would open up a large field of inquiry with 

 respect to the potency of the pollen in all plants which have 

 two sets of stamens — viz., longer and shorter. Can you for- 

 give me for troubling you at such unreasonable length ? But 

 it is such waste of time to experiment without some guiding 

 light. I do not know whether you have attended particularly 

 to Melastoma ; if you have not, perhaps Hooker or Oliver 

 may have done so. I should be very grateful for any infor- 

 mation, as it will guide future experiments. 



P.S. — Do you happen to know, when there are only four 

 stamens, whether it is the petal or sepal-facers which are 

 preserved ? and whether in the four-stamened forms the pistil 

 is rectangularly bent or is straight ? 



Letter 621 To Asa Gray. 



Down, Feb. 16th [1862?]. 



I have been trying a few experiments on Melastomads ; 

 and they seem to indicate that the pollen of the two curious 



1 According to Willis, Flowering Plants and Ferns, 1897, Vol. II., 

 p. 252, the style in Monochcetum, " at first bent downwards, moves slowly 

 up till horizontal." 



1 No reply by Mr. Bentham to this or the following queries has been 

 found. 



