18 SPONTANEOUS GENERATION. 



centimetres] of water, was boiled 20' [20 minutes] in a bolt- 

 head and hermetically sealed. A film formed on the fourth, and 

 the flask was opened on the eleventh day, when there was a 

 distinct rush of air outwards. Large numbers of Bacteriums 

 (fig. 6, a, b, c, d) were found, also small spherical bodies, (fig. 5, 

 a,) with ciliary motions and oval bodies like Kolpoda, contain- 

 incr what appeared to be Bacteriums; one of these Kolpoda-like 

 bodies moved with cilia. (Fig. 5, c, d.} 



Expts. xvi., xvii., xviii., xix., (B,) March 20th, were made 

 with juice of beef and water in flasks of 550 cub. cent, capacity ; 



Fig. 5. a, a group of Monads ; minute spherical 

 bodies, constantly agitating, as if moved by the vi- 

 brations of thread-like appendages (cilia) ; b, Vibrio 

 rugula. 500 diam. A very common thing in all 

 decaying fluid matter, forming a sort of scum at a 

 certain period of the decomposition. Seen -with 

 the lower powers of the microscope, the scum appears to scintillate all over its 

 surface ; and if higher powers are applied, this phenomenon is found to be due 

 to the rapid whirling motion of these minute, curved, moniliform (bead-like) 

 strings, as they shoot, with greater or less velocity, backward and forwards 

 across the vision. Their curved form produces the appearance of a screw or 

 spiral as they vibrate in their path through the fluid, and the alternate appear- 

 ance and disappearance of the highly refractive bead-like grains has the effect 

 of sudden flashes of light, or scintillations. When there are only four or five 

 beads in a string, the velocity of their movements is almost inconceivable, and 

 their structure cannot be ascertained until they stop to change or reverse the 

 whirl, and return upon the path in which they came. Most frequently, however, 

 there are six or eight beads in a string; and in this condition, although their 

 speed is less than that of the shorter ones, yet they swim very rapidly ; but as 

 the string is found to be longer, so do we see also that the motion is proportion- 

 ately slower ; and finally we may meet with those very long ones which wind 

 their way with the leisurely undulations of a snake. 



c, d, " Kolpoda-like bodies," seen in Expt. xii. The presence of movable cilia 

 on a body is the most indubitable evidence that it is in a living condition ; but 

 whether it is an animal or plant must be determined by its internal structure. 

 Professor Wyman's unpublished figures, from which these two were copied, by 

 his kind permission, do not indicate an animal any more than a vegetable nature. 

 They would seem to be allied to those extremely low forms of life, whose position 

 either in the animal or vegetable kingdom is to be hereafter determined by 

 more searching investigations than have thus far been made. 



