1692 



Journal of Applied Microscopy 



ture. The common pond scum, Spirogyra, is an excellent type with which to 

 practice medium and high power projection. The vegetative stage affords fine 

 examples of cell division, many species exhibit the nuclei clearly, and the repro- 

 ductive stages are brought out with great clearness, even to the structure of the 

 zygospores. Vaucheria is an easy and instructive object. Chara or Nitella 

 affords opportunity to use any one or all of a series of lenses, beginning with a 

 quarter-size projector, such as is in common use for lantern slides, which shows 

 a section of the plant three inches or more long and magnified about forty dia- 



Fig. I. Hydra (x 650) : class making drawing. Illumination of screen by 

 porte-lumiere, of room from window. One exposure. 



meters at thirty feet, then low power objectives for gross structure, higher power 

 for young or mature antheridia and oogonia, and high power objectives for sper- 

 matic filaments and the circulation of protoplasm. 



Marchantias and mosses, the prothallia of ferns and the same with a young 

 sporophyte attached, embryo plants, and parts or sections of large specimens 

 present a wide range of types. The physiological action of green plants under 

 the stimulus of sunlight can be as perfectly shown with the electric arc light as 



