298 



COMMUNICATIONS BY 



COMMUNICATIONS BY H. WEEKE£ 9 ESQ 



Referred to at page 262 



Dkab Sir — Since the details of my first experiments on the pro- 

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

 through the medium of the " Proceedings of the London Electrical 

 Society," session of 1842, Sec., and, about 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 frequently modified by va- 

 riations in regard to the form of the experiments, and their correl- 

 ative arrangements. 



Incident to the period 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 cir- 

 cumstances under which my latter experiments have been con- 

 ducted ; and although, in my own estimation, the evidence it yields 

 is not one whit more conclusive than the results formerly made 

 known, it is clearly free from certain objections urged against the 

 first experiments, and is selected under an impression that, if these 

 conditions fail to show that the electric current is the agent by 

 Which the laws of organization have been promoted, then we have 

 — maugre the Baconian philosophy — already trusted too much to 

 experimental facts, with a view to the establishment of truth. 



It is by no means easy, even if practicable, independent of 

 sketches, to convey a precise idea of the apparatus employed in 

 the experiment I am about to communicate. I will, nevertheless, 

 attempt to describe it with as much brevity and plainness as pos- 

 sible. In the first place, I must mention that the arrangements 

 were originally of a three-fold character :— 1st. A close vessel 

 containing a saline solution, and above it an artificial atmosphere ; 

 2d. An open vessel containing the same solution, both acted upon 

 by the same current passing through them from a voltaic battery ; 

 3d. Two glass jais standing on the same table, as negative tests, 

 and in every way corresponding with the respective primar} 7 ves- 

 sels, excepting that they had no wire appendages, and were un- 

 elec trifled. 



The close vessel consists of a wide-mouthed glass jar, capable 

 of containing a pint and a half of liquid, and is manufactured from 

 the purest and most transparent material. From the top, or shout, 

 der of this jar, ascends to the height of an inch from the surround- 

 ing surface, a remarkably stout and strong neck, which presents 



