INFTJSOKIA. 109 



is struck with surprise when he first contemplates this little creature, 

 which, under the greatest magnifying power, only presents the appear- 

 ance of a thin black line, fashioned like a corkscrew, 

 which every instant turns upon itself with marvellous 

 velocity, such as the eye can scarcely follow, or the 

 mind divine the cause which produces this startling 



r Fi<*. 32. Spirillum 



phenomenon. tonraoyant (Ehr.), 



The Monads are other infusorial animalcules which magniiie 

 make an early appearance in vegetable infusions. They constitute a 

 family that are destitute of any covering. The substance of their 

 bodies can swallow itself, or draw itself out more or less ; many of 

 the whip-like filaments serve as organs of locomotion. They are 

 sometimes provided with lateral appendages disposed as a kind of 

 tail. Their organization is extremely simple ; their whip-like filaments 

 are so fine as to be scarcely perceptible, their length being sometimes 

 double and even quadruple the length of the animal itself. 



The Lentille Monad (Fig. 33) is a species which is frequently met 

 with in vegetable and animal infusions. The older microscopists had 

 it indicated under the form of a globule, moving in a slow and 

 vacillating manner. The globule is formed of a homogeneous trans- 

 parent substance, swollen into tubercles on its surface, and throws out 

 obliquely a whip-like filament,, three, four, or even five times the 

 length of the body of the Monad. 



The Cereomonad of Davaine was discovered by this gentleman in 

 the still warm ejections of cholera patients. Its body 

 is pyriform, having, in front, a vibratile filament, very 

 long, very flexible, and easily agitated. Behind the 

 body there is a thicker straight filament attaching itself 

 sometimes to neighbouring corpuscles, round which, 

 in this case, the Cereomonad oscillates like the ball of Fig 

 a pendulum round its stem. 



The Volvocinese are inhabitants of fresh limpid water 100 times ' 

 full of confervse and other aquatic plants. The Volvocinede are, ac- 

 cording to Dujardin, animalcules of a green or yellowish brown colour, 

 regularly disseminated in the thickness and near the surface of a 

 gelatinous and transparent globe, which would become hollow and be 

 filled with water in its perfect state. In this state, from five to eight 

 smaller globules, with the same organization, appear destined to 



