68 Mr. HowAno's Account of a Microfcopical Invcftigallon 



If a piftil be feparated from the expanded flower with grains of 

 ■pollen adhering to it, the latter will be found already expanded to 

 a Ipheroid. Cover the whole with a drop of fpirit on the glafs, the 

 piftil is not affefted in any way, but fome of the grains quit it and 

 revolve on their axes. When thefe are exhaufted, the addition of 

 more fpirit excites others : after a few minutes, fome of thofe firft 

 excited begin to put out a fmall thread, which gradually elongating, 

 the grain diminifhes in proportion, until it is entirely drawn out 

 into a vermicular fibre, which again is prefently difflpated into par- 

 ticles too minute to be feen in the now opake medium. The liquor 

 from the tube of the piftil, and a folution of fugar in water, were 

 alfo found to produce this evolution in very mature grains 

 from the anther. It alfo fometimes takes place in the twinkling of 

 an eye, fo as to be fcarcely traced in fome few grains out of a 

 number put into fpirit at once. Thofe which have been fome time 

 in contadt with the piftil are always mofl: fluggilh in their evo- 

 lution. 



5. Car ex acuta. 



Anthers oblong, crumbhng. Pollen angular, opake, with apparent 

 perforations. It dilates in fpirit and remains ftationary, but eje6ls 

 numerous minute particles in rapid fucceffion from its furface. 

 When it has become tranfparent it appears as if filled with feeds. 



The preceding may ferve for examples of thefe phaenomena ; but 

 there was not one among the various fpecies I examined, which did 

 not exhibit them in a greater or lefs degree. Yet various other parts 

 of the flower, immerled in fpirit under the microfcope, did not be- 

 tray the fmalleft veftige of them. 



The proper fpirit for this purpofe feems to be a mixture of one 

 part pure fpirit of wine with two of water. A ftronger fpirit, or 

 even fpirit of wine alone, may fometimes be required when we ope- 

 rate upon a pollen which has, by any means, became previoufly 

 6 faturated 



