70 Mr. Howard's Account of a Mlcrofcoptcal Jnvejllgation 



tlon?, that the pollen of vegetables is in all cafes fimilarly aded 

 upon by water and by fpirit of wine, it will follow, — 



T, That each grain of pollen in the anther is an organic body, 

 vaiioufly conftrucled in various fpecies, and containing 



n VefTels or pores capable of imbibing water, of diftending thereby 

 and contrading again when it quits them; in which particulars they 

 refemble fponge, &c. 



h A parenchyma, confifting of fome fubftance (of greater fpecific 

 gravity than water, and infoluble therein), which is emitted with a 

 greater or lefs degree of force when the ftimulus of alcohol is applied 

 to the abforbent veflels. This fubdance is either in part foluble in 

 alcohol, or the grains contain 



c An eirential oil or refin, to which they owe their colour and 

 odour. 



2. That there exifts in the grains of pollen, in a very eminent 

 -.degree, that property of vegetables called irritability, which they 



are capable of retaining for a certain time after feparation from the 

 anther. 



3. That alcohol is the proper flimulus by which this irritability 

 may be excited, and the texture of the pollen in fome manner deve- 

 loped in confequence thereof. I prefer this method of accounting 

 for the appearances that take place when the pollen is immerfed in 

 fpirit ^o another that might be fuppofed on chemical principles, 

 beifig a flared, that any one who has once infpecled the procefs w]ll 

 be fatisfied that fomething more than mere folution or chemical 

 decompolition takes place therein, and that the vital principle of 

 the pollen is the chief agent. 



The hquor from the tube of the pidil and the folution of fugar 



were, indeed, found to bring on the evolution of the pollen oiCadtus 



jla^eL in a flower manner than fpirit; but when we confidcr how 



fpeedily 



