Vr. H. WEEKES, ESQ. 193 



instructed for the occasion, and the entire proceeding has been 

 jafined to a retired room kept constantly locked, no one having 

 access unless accompanied by myself. My general habit has 

 been to visit the arrangement once in two days, for the purpose 

 of noting the progress, supplying the battery with crystals of 

 sulphate of copper, making good the loss of fluids caused by the 

 evaporation, &c 



1. October 19th, 1S43 — one hundred and sixty-six days from 

 the commencement of the experiment — the first acari seen in 

 connexion therewith, six in number and nearly full-grown, were 

 discovered on the outside of the open glass vesseL On removing 

 t^o pieces of card which had been laid over the mouth of this 

 vessel, several fine specimens were found inhabiting the under 

 surfaces, and others completely developed and in active motion 

 liere and there within the glass. 



October 20th. — Making my visit at an hour when a more 

 favourable light entered the room, swarms of acari were found on 

 the cards, about the glass tumbler, both within and without, and 

 also on the platform of the apparatus. At this identical hour 

 Dr. J. Black favoured me with a call, inspected the arrangements, 

 and received six living specimens of the acams produced from 

 solution in the open vessel. No trace of insect life could at this 

 time be discovered in the close vessel with an oxygen atmosphere. 

 The solution in the open vessel had undergone very slight change 

 of colour, but exhibited a multitude of minute and beautifully 

 coloured crystals with a prevailing tinge of crimson. The solu- 

 tion beneath the oxygen atmosphere, about ten days after the 

 voltaic current began to traverse it, had assumed a reddish-browu 

 appearance, which gradually darkened in colour until scarcely 

 any light could be transmitted through it, or the ascent of gas 

 from either of the electrodes perceived. 



2. Myriads of acari continued to be developed from the solu- 

 tion in the open vessel until the 20th of August, 1S43, when it 

 was found expedient to determine this division of the experiment, 

 and confine the operation of the electric current solely to the 



A 



