462 NOTES ON PLANTS INDIGENOUS TO SYDNEY. 



and Correa speciosa, in order to notice the comparative effect of 

 moisture on their pollen. In the first two the anthers and pollen 

 are protected, in the last they are fully exposed. I placed each 

 kind of pollen in a watch-glass, in a dry place, till I supposed that 

 as nearly as possible they were equally free from moisture ; and 

 then sprinkled them lightly upon the surfaces of three basins of 

 water. That of Lyonsia became saturated and sank level with the 

 water in a few minutes. That of Cryptandra in two hours. That 

 of Correa remained floating upon the surface till the following day 

 as though a film of air intervened between it and the water. The 

 effect upon pollen, becoming saturated so readily as that of Lyonsia, 

 would no doubt, especially under a warm sun, be to cause it to 

 swell and burst in an irregular manner, in place of emitting 

 pollen-tubes in the usual way ; and this would destroy its fertilising 

 power, for it is essential to the conveyance of the particles of 

 fovilla3 to the ovule, that the pollen grains be kept intact ; so 

 that it shall escape by means of the pollen-tubes only. In an 

 experiment with fresh pollen taken from the same three plants, the 

 result was the same, with the exception, that the time required 

 for the saturation of the pollen of Lyonsia and Cryptandra was 

 longer, but still in the same order as in the previous trial. 



I must say, that as these experiments were made under 

 some difficulty, and in rather a rough way, I do not consider them 

 conclusive, I merely mention them as a suggestion to any one who 

 may be inclined to carry them out in a more perfect way. It is 

 however, my intention during the present summer to make many, 

 more carefully, in the same direction. 



