BY WILLIAM J. BYRAM. 17 



primitive gullet, and two pulsating vacuoles, one at each end. 

 These vacuoles, shown separately in the diagram, are more 

 complicated than in the amoeba or sun-animalcule, for as they 

 pulsate we notice from six to ten delicate spindle-shaped spaces 

 forming star-like vacuoles. The paramoecium reproduces by 

 subdivision, and in it also, as the researches of Hertwig and 

 others have shown, we have the same phenomenon of the union 

 of two individuals as a momentum to renewed powers of feeding 

 and subdividing. Hertwig says that the union brings about a 

 complete reorganisation of the nuclear apparatus and at the same 

 time of the infasorian. The individuals which have thus become 

 rejuvenated have regained the capacity of multiplying enormously 

 by means of division, until again the necessity for a new 

 conjugation arises. During a period of six and a-half days a 

 single individual, when provided with sufficient nourishment, 

 divides thirteen times, that is to say, produces about 8,000 

 descendants. 



If we have water weeds under examination, we often 

 see pendent from them a number of beautiful little 

 crystal bells on flexile stalks, which expand to a straight line and 

 suddenly contract in corkscrew fashion as the bell darts 

 downwards. These are the vorticellae, or bell flower animalcules, 

 another example of the ciliated infusoria. We notice that each 

 bell is crowned with a circlet of cilia in rapid vibration, and as 

 they vibrate little whirlpools or vortices are produced in the 

 surrounding water. Like all the other lowly forms that we have 

 reviewed, the vorticella reproduces by subdivision, and when a 

 colony gets too large some of the members of it detach them- 

 selves from their stalks and swim away to find fresh pastures 

 elsewhere. This is a mere method of dispersion, but at times, if 

 we watch the bells closely, we observe a cluster of buds at the 

 base of certain of them, which looks something like a minute 

 crystal bunch of grapes. These buds develop cilia, detach 

 themselves, and after swimming about for a time approach the 

 bells and gradually fuse into them. This is another phase of 

 conjugation, and after it the vorticella acquires quickened powers 

 of feeding and subdividing. As instances of other infusors we 

 may notice the opalina and gregarina, which are curious as 

 showing how species of infusoria can become parasitic. The 

 opalina is found in the large intestine of the common frog, where 

 it is nourished by the partially digested food of its host. The 



