THE CELL. 47 



sexual differences (physiological at least) of which we are yet ig- 

 norant. The chromatophores often contain bright spots, called 

 pyrenoids, and are instrumental in producing starch, which, as 

 minute granules, occurs surrounding the pyrenoids. The cell ex- 

 hibits cell-wall, primordial-utricle, protoplasm, nucleus, chromato- 

 phores, starch grains, pyrenoids, and chlorophyl. 



Habitat. Spirogyra may be found in ponds and slow-running 

 creeks, and is widely distributed. It is somewhat smooth and slimy 

 to the touch. 



Laboratory exercise No. 8. Obtain from some pond or brook a quan- 

 tity of Sphogyra, placing it in a large jar with water. Examine with 

 H. P., observing the filaments composed of cells attached end to end. 

 Make a study of a single cell. Observe the spiral arrangement of the 

 chloropiusts. Use the 1-12-inch objective and search for the pyrenoids 

 and starch granules. Find cells in the process of fission. This is to be 

 observed where the cells are much shorter than normal size. Irrigate 

 with a drop of acetic acid, and search for a nucleus. Make drawings 

 to illustrate filaments and a single cell containing nucleus, chloroplasts, 

 and cell-wall. 



A STUDY OF ANIMAL CELLS. 



AMCEBA. 



The Amoeba is a unicellular animal devoid of a cell-wall, having 

 the power to produce pseudopodia, and reproducing by normal .fis- 

 sion. 



Classification: 



Kingdom Animal. 



Series Protozoa. 



Sub-kingdom Protozoa. 

 Class Monera. 



Order Amoebea. 



Genus Amoeba. 



Species Amceba proteus. 



Life History and Morphology. The Amoeba is an animal which 

 appropriates food without a mouth, digests without a stoimich, 

 breathes without lungs, and has sensation without a nervous sys- 

 tem. It is simply a mass of protoplasm consisting of cytoplasm and 



