189 



COMMUNICATIONS BY W. H. WEEKES, ESQ. 



Referred to at page 120. 



Dear Sir, — Since the details of my first experimeuts on the 

 production of acari in close atmospheres were given to the world, 

 through the medium of the " Proceedings of the London Elec- 

 trical Society," session of 1842, &c., and, ahout the same time, 

 circulated among my scientific friends, in a reprint from the 

 above-named work, as stated by you in a foot note to page 187, 

 first edition of the Vestiges, the subject has continued to occupy 

 my attention, while the nature of my researches has been fre- 

 quently modified by variations in regard to the form of the 

 experiments, and their correlative arrangements. 



Incident to the petiod included by the last three years, many 

 experiments on the subject have been completed ; others are even 

 yet in progress ; and, however rigid were the conditions in any 

 case adopted, thus much is certain, that the acari have invariably 

 appeared in the several solutions under electrical influence, while their 

 absence has been as invariably remarked, in spite of the nicest 

 scrutiny, in all negative tests provided to accompany the respective 

 primary experiments. 



The following may be taken as an example of the stringent 

 circumstances under which my latter experiments have been 

 conducted ; and although, in my own estimation, the evidence it 

 yields is not one whit more conclusive than the results formerly 



