NAURE STUDY IN SCHOOLS. lV>5 



into a single mass. From this mass are developed nucleated cells, which 

 gradually become spindle-shaped. Upon the rupture of the cyst, the spindle- 

 shaped bodies escape. These spindles produce amoeboid bodies which, in turn, 

 develop into the original gregarina. Thus three distinct forms intervene be- 

 tween the adult forms in the progress of development. It will thus be seen 

 that the offspring for three generations do not resemble the original parent 

 form, and this alternation of generation, as this and similar methods of re- 

 production are called, begins quite low in the scale of animal life. 



PROVINCE INFUSORIA. 



Infusorial animalcules. 



They are the highest of the Protozoa, as they possess the most complica- 

 ted structure. They are divided into two groups. 



FLAGELLATA. TAILED INFUSORIA. 



All agree in possessing one or more elongated, whip-like cilia, or long, 

 slender appendages with which they move or gather their food. Some move 

 freely about, but others are attached together in colonies, and in structure 

 somewhat resembles the sponges. In fact, they are considered by some authors 

 to intergrade with the sponges, but, as will be seen in a forthcoming article, 

 there is considerable difference between the two groups. 



ORDER CILIATA. CILIATED INFUSORIA. 



This is a large order of animalcules, all of which possess cilia which are 

 used as locomotive organs. 



PARAMOECIUM, OR SLIPPER INFUSORIA. 



Among the many species of ciliated animalcules we find as a typical 

 form, the slipper infusoria. If we cut up hay in small pieces and put it in 

 water in a warm place, we will find upon examining this water after two 

 or three days, that it is filled with animalcules, many of which will be the 

 species in question. 



Form. The slipper infusoria differs from the amoeba inasmuch as it is 

 unchanging in form. It is much longer than wide, rounded at one extrem- 

 ity and pointed at the other. Upon watching the animal for a minute, it 

 will be seen that it moves with the larger end foremost, and we thus natu- 



