72 HONEY-DEW. 



spheric stroke, which has injured their health. 

 Dr. DARWIN stands in this class. Others have 

 viewed it as a kind of vegetable perspiration, 

 which the trees emit for their relief in sultry 

 weather ; its appearance being never observed in 

 a cold ungenial summer. Dr. EVANS is of this 

 opinion, and makes the following comparative re- 

 mark : " As the glutinous sweat of the negro 

 enables him to bear the fervours of his native 

 clime, far better than the lymph-perspiring Euro- 

 pean ; so the saccharine dew of the orange, and 

 the fragrant gum of the Cretan cistus, may pre- 

 serve them amidst the heats even of the torrid 

 zone." Mr. CURTIS has given it as his opinion 

 that the honey-dew is an excrementitious matter, 

 voided by the aphis or vine-fretter, an insect 

 which he regards as the general cause of what are 

 called blights. He assures us that he never, in a 

 single instance, observed the honey-dew unat- 

 tended with aphids. 



I believe it will be found that there are at least 

 two sorts of honey-dew ; the one a secretion from the 

 surface of the leaf, occasioned by one of the causes 

 just alluded to, the other a deposition from the body 

 of the aphis. Sir J. E. SMITH observes of the 

 sensible perspiration of plants, that " when watery, 

 it can be considered only as a condensation of 

 their insensible evaporation, perhaps from some 

 sudden change in the atmosphere. Groves of 



