82 TYPE STUDIES 



2. The cytoplasm, granular in structure, probably containing one or 

 more vacuoles which were filled with cell sap. 



3. The cell walls separating the protoplasts from one another. 



C. Find a nucleus in the midst of division (metaphase of mitosis). Note : 



1. That the chromatin has become organized into a number of rod- 

 shaped bodies, chromosomes, which are grouped in the center of the 

 cell, and that the nuclear membrane has disappeared. Draw. 



2. That the chromosomes are arranged in a plate, equatorial plate, be- 

 tween the poles of a sjnndle composed of delicate spindle fibers. Try 

 to count the chromosomes. 



3. Search for evidence of a lengthwise division of the chromosomes 

 into daughter chromosomes. Draw. 



D. Find a cell in which the daughter chromosomes have separated into 

 two sets and are passing towards or have been gathered at the poles of 

 the spindle (anaphase of mitosis). Note : 



1. The separation of the daughter chromosomes into two groups and 

 their passing to the poles of the spindle to form the daughter nuclei. 

 Try to count the chromosomes in each daughter group and compare 

 with the count at the equatorial plate. Draw. 



2. The persistence of the spindle between the groups of daughter 

 chromosomes. 



3. The appearance of a delicate plate across the spindle, finally reach- 

 ing the sides of the cell. This is the cell plate and marks the position 

 of the new cell wall which will be formed, dividing the mother cell 

 into two daughter cells, each with a nucleus. Draw. 



E. Find a later stage after the daughter nuclei have become organized as 

 resting nuclei and the cell division is completed. 



F. Study the beginnings of nuclear division (prophase of mitosis) before 

 the spindle is formed and the chromosomes are gathered at the equa- 

 torial plate (metaphase). Note : 



1. That the loose chromatin network becomes a thread, spirem. 



2. That this thread divides transversely into segments, which are the 

 chromosomes. Draw. 



3. That the spindle is developed from accumulations of protoplasm 

 (kinoplasm) at two poles outside of the nuclear membrane. Draw. 



66. Characteristics of some organic compounds found in plant cells. 



Certain organic compounds will be met so frequently in cell 

 studies upon the lower plants that some of their characteristics 

 should be known. They fall into two great classes : (1) the carho- 

 ]i7jdmtes, composed of carbon, oxygen, and hydrogen, represented 



