Roijal Microseojoieal Society. 263 



kind at Eock Ferry, whicli at the time showed only very feehle 

 signs of any hfe, and certainly no monads. We watched the 

 result; and, to our great surprise, in three days the required 

 monad appeared in remarkable vigour and daily increasing abun- 

 dance, enabling us to complete our researches into its cycle of 

 development. Whilst at the same time another, and remarkable 

 form, whose history we have since completed, and which had only 

 very feebly shown itself before the drying up of our infusion, now 

 showed great vigour, and eventually survived and predominated, 

 evidently very much at the expense of the former. 



This may be accounted for in two ways at least. First, the 

 germs — which we have proved to exist in the development of this 

 form — gave origin to new monads when the caked mass was 

 broken up by solution and set them free in normal conditions ; and 

 second, we are strongly inclined to believe that hundreds of milhons 

 of the adult forms were only desiccated by the drying up, and 

 were resuscitated when the fluid was restored; an opinion which 

 subsequent experiment has done much to confirm. 



With reference to the immediately asserted, and eventually 

 absolutely secured ascendency of the new form above referred to, 

 after the remoistening of the dried maceration, it is evident that 

 some new conditions had arisen in consequence of the drying up 

 of the pabulum, and its subsequent remoistening, which in the 

 struggle for existence made it the fittest to survive. 



The form we now describe has occupied our attention for at 

 least three years, but some points of difficulty each year presented 

 themselves, and we have delayed any reference to it until we had 

 learned as much concerning it as we deemed possible. It is in fact 

 the form incidentally referred to in our first paper,* and drawn, in 

 various positions, at a, a, &c., Fig. 1, PI. XXIV., vol. x,, of the 

 * Monthly Microscopical Journal.' 



It is a form possessed of more distinctive and distinguishable 

 structure than any other so low in the scale of life with which we 

 are acquainted. Its most marked peculiarities may be summarized 

 with the aid of Fig. 1. The sarcode is invested with a distinct 

 hyaline envelope, perfectly structureless to our best appliances, and 

 sharply distinguishable from the protoplasm of the body ; two flagella, 

 inserted into what appears like a special organ of locomotion ; a 

 large central disk or nucleus-like body, a ; numerous protoplasmic 

 granules, h, the function of which we shall shortly explain ; a pair 

 of "snapping" eye-spots, c;t and occasionally some remarkable 

 club-like appendages to the anterior part of the body, the nature of 

 which we have failed to ascertain ; and to which we shall again refer. 



The body is oval, the pair of flagella with which it is furnished 



* ' M. M. J.,' vol. X., p. 53. 

 t Ibid., vol. xi., p. 8. 



u 2 



