VOLVOCINE^:. 



VOLVOX GLOBATOR. 



This Alga is to be found swimming freely in fresh- 

 water ponds, mostly in exposed situations : it is of such 

 a size that its simple spherical body can be recognised 

 with the naked eye. 



Mount one or more in water in a hollow-ground slide 

 without a cover-slip, and examine under a low power : 

 observe 



1. The hollow spherical form of the whole organism 

 (coenobium). 



2. Its rotating movements in the water. 



3. The tissue of the hollow sphere, consisting of 

 numerous cells forming a single layer, and for the most 

 part similar to one another. 



4. The daughter-coenobia of various sizes in 

 different specimens : their number is usually eight. 

 They may be seen projecting into, or even almost 

 filling, the cavity of the parent. 



Mount a coenobium in water under a cover-slip, and 

 examine it in detail under a high power : it will of 

 course be squeezed flat by pressure of the cover-slip : 

 in the tissue thus flattened observe 



1. The ordinary cells of the coenobium, each consisting 

 of a protoplasmic body with green chromatophore, a 



