DIRECTIONS FOE LABORATORY WORK 767 



(5) Sketch (18) section of full grown ovum of blood-starfish (Hen- 

 ricia sanguineolenta) ; noting especially the multinucleolated condition 

 of the nucleus, and the graimlo-alveolar character of the cytoplasm. The 

 eggs of many amphibians during later growth stages also have a multi- 

 nucleolated nucleus. 



Sketch (19) a small area of this cytoplasm demonstrated with an oil 

 immersion lens. 



(6) LIVING PROTOPLASM. Mount a drop of a hay infusion culture 

 of amebae and paramecia. 



Examine first a paramecium. Observe ciliary movement. When the 

 protozoon comes to rest, note exoplasm, endoplasm, metaplasm, nuclei 

 (macronucleus and micronucleus), contractile vacuoles and the finely 

 granulo-alveolar character of the cytoplasm. Sketch (20). Observe the 

 cytoplasmic changes occurring during the death of the animal. 



In an ameba, observe manner of progression (ameboid movement), 

 the nucleus, food vacuoles, water and contractile vacuoles; and note the 

 homogeneous or very finely granular character of the protoplasm. Sketch 

 (21). Observe the protoplasmic changes during death. 



(Unless otherwise specified all drawings are in future to be made 

 with the high power of the microscope.) 



III. CELL DIVISION 



(A) AMITOSIS (Akaryokinesis, Direct division). , 



(1) Sketch (22) several stages in the amitotic division of the nu- 

 cleus (from demonstration preparation, e.g., ductuli efferentes of epi- 

 didymis of mouse; mesenchyma of young embryo 10 da. turtle em- 

 bryo). Study direct division or 'budding* of yeast cells. 



(2) Sketch (23) a multinucleated ('giant') cell from the yolk sac 

 of a 10 to 15 mm. pig embryo (demonstration preparation). These cells 

 arise from mononucleated cells through amitotic division of the nucleus. 



(B) MITOSIS (Karyokinesis, Indirect division). 



(I) Sketch (2\) successive steps in the mitotic division of cells from 

 the root tip of some vigorously growing young plant (e.g., dog-tooth 

 violet, onion, hyacinth, spiderwort (tradescantia), etc.): 



(a) cell with nucleus in the resting condition. 



(b) nucleus with close spireme. 



(c) with loose spireme. 



