THE BEGINNINGS OF IIFE. 251 



same time a very f.^int and almost imperceptible mass 

 ('nucleus') began to reveal itself near the centre of 

 the organism, and when examined with a magnifying 

 power of 1670 diameters, a lateral aperture (mouth) 

 80W in diameter was seen which was fringed by short 

 active cilia, arranged like the spokes of a wheel. These 

 peculiarities correspond very closely with those of an 

 embryo Nassula. Very many were seen with similar 

 characters, and multitudes existed in all conditions 

 intermediate between this stage and that of the simpler 

 organism which first emerged from the cyst. No 

 further stages, however, could be watched, as at this 

 time some change took place in the infusion which 

 proved fatal to all the free Infusoria and also to the 

 multitudes of embryos which were at the time deve- 

 loping in the pellicle. These became more minutely 

 granular and opaque, their movements ceased, and the 

 cyst-wall grew thicker. This phase of development 

 disappeared, therefore, almost as suddenly and myste- 

 riously as it had appeared. The cysts were examined 

 from time to time for many weeks afterwards, but 

 they seemed to undergo no further change \ 



^ In a maceration which was subsequently made during very cold 

 weather, when the temperature of the room, even during the day, was 

 rarely higher than 53° F, very large AmoebDe, sdme of which were yi-^" in 

 diameter, and visible to the naked eye, were produced from the pulpy, 

 under portions of the pellicle. They fonned great masses of living, 

 granular jelly of the simplest description — too large to move as a whole, 

 though fluxes of portions of their semi-fluid body-substance were con- 

 tinually taking place in different directions. 



