INDEX AND GLOSSARY. 413 



Family 1. Closteriese. Ceils single, elongated, never spi- 

 nous, frequently not constricted in the middle; sporangia 

 smooth. 



Gen. Closterium. Penium. Tetmemorus. Docidium. 

 Spirotsenia. 



Family 2. Cosmariese. Cells single, constricted in the mid- 

 dle ; sporangia spinous or tuberculated. 



Gen. Micrasterias. Euastrum. Cosmariurn. Xanthidium. 

 Arthrodesmus. Staurastrum. Didymocladon. 



Family 3. Desmidese. Cells united into a filament , sporan- 

 gia spherical, smooth. 



Gen. Hyalotheca. Didymoprium. Desmidium. Aptogo- 

 num. Sphoerozosma. 



Family 4. Ankistrodesmise. Cells elongated, entire, small, 

 in fagot-like groups. 



Gen. Ankistrodesmus. 



Family 5. Pediastrese. Cells grouped in form of a disk or 

 star, or side by side in one or two short rows. 



Gen. Pediastrum. Monactinus. Scenedesmus. 



Diabetic sugar, 305. 



Diagnosis, microscope in, 295. 



Diaphragm, Rotary, 32. An instrument for intercepting 

 excessive ra} r s of light. 



Diaphragm, cylinder, 32. 

 " graduating, 33. 



" iris, 33. 



Diatomacese, 56, 94, 141. A family of Algae. 



Diffraction of Light, 54. Disturbance of the ray by the 

 edge of an opaque body. 



Difflugia, 159. 



Diphtheritic exudation, 260. 



Discrimination of blood, 299. 



Distomum, 335 (Gr. dis, double ; stomata,, mouths). 



Disease germs, 339. 



Dotted cells, 130. 

 44 ducts, 131. 



Double Refraction^ 91. The power some crystals have of 

 exhibiting two images. 



Double staining, 347. 



