2G2 Transactions of the 



concerning them wliich, altliougli without explanation or apparent 

 bearing at present, seem to us of sufficient importance for note. 

 Our first maceration was a cod's head ; it was freely exposed to 

 the air, but excluded from the light. For two months nothing 

 at all remarkable presented itself. Abundance of Bacteria termo, 

 B. lineola, and Amoebae were found. But at the expiration of the 

 twelfth week the form to be described in this paper gradually 

 appeared — survived for three months and two weeks, to the almost 

 complete exclusion eventually of other forms — and then was sup- 

 planted by other monads, some of which have been described by us 

 in former papers. 



This maceration was made from ordinary water supplied by the 

 company on the Cheshire side of the Mersey. The same year, in 

 the same place, another cod's head, and the head of a salmon were 

 macerated in separate vessels. It was later in the year, and the 

 production of vital forms was slower ; yet in the course of four 

 months the same phenomena as those described above took place ; 

 the only difference being that the form that we are about to describe 

 did not persist so long. 



In tlie autumn of the same year another cod's head maceration 

 was made in Liverpool from the ordinary water supplied to the 

 town. This up to the spring of the following year showed no 

 trace of the form in question, nor indeed of any monad, but 

 swarmed persistently with gigantic specimens of the Spirillum 

 volutans. After this several other macerations were made, in the 

 same place, and the form we desired appeared, but no spirilla could 

 be discovered. While a maceration of salmon's head made in April, 

 1873, under the same circumstances at the same place (viz. on the 

 Lancashire side of the Mersey), was found in April, 1874, to swarm 

 with the peculiar monad form in question ; but another infusion of 

 herring made at Eock Ferry (on the Cheshire side) late in the 

 summer of 1873 has not yet shown the monad we hoped for. 

 What determines their appearance or non-appearance we have no 

 data even to surmise; but it is a subject which is securing our 

 attention. 



Another incident in our last summer's work may be mentioned. 

 We always work from a small quantity of the large vessel of 

 decaying matter which we can keep at hand. During the early 

 summer the intense and continued heat evaporated all the fluid 

 from the salmon's head infusion without our knowledge. The form 

 at which we were working had been in it in great profusion. It 

 was growing less abundant in our small working tank, and we 

 feared that we must wait another year to finish our inquiries. But 

 we led a forlorn hope, and took the hard, porous, dried, papier- 

 mache-like mass which formed the dry residuum of the infusion, 

 and determined to put it into an exhausted maceration of the same 



