OF ANIMALCULES. 97 



plane ; the four centre ones are generally larger 

 than those which surround them ; and the diameters of 

 the three smaller balls are only equal to the two larger 

 centre ones to which they are attached 5 the external 

 corners are consequently vacant. As these animalcules 

 swim and revolve in the water, they occasionally present 

 a side-view to the observer, when the circumference of 

 the larger central globules may be seen projecting be- 

 yond the others. Sometimes the cluster appears irregu- 

 lar, as shewn in figure 95 : this happens when the larger 

 animalcules have arrived at maturity, and some of them are 

 separated from the cluster. When they are all of equal 

 diameters, the group divides across the middle, both 

 vertically and horizontally, and separates into four clus- 

 ters, each consisting of four animalcules. As soon as a 

 cluster has separated, the respective animalcules increase 

 in size, and in a short time their surfaces appear decussated, 

 and they severally begin to form into regular clusters, 

 like the original one to which they belonged. They are 

 of a beautiful transparent green colour, and in swim- 

 ming the globules often appear of an ellipsoidal figure : 

 their forms are so simple, and so different from animated 

 beings visible to ordinary vision, that it would be difficult 

 to bring our reason to admit of their vitality, were not 

 their spontaneous motion clearly ascertained. The dia- 

 meters of the clusters vary from l-350th to 1 -200th of an 

 inch. Some fine specimens I have seen even larger ; 

 hence the average size of an individual globule is about 

 1- 1200th of an inch. They are found near the surface of 



