II. REPRODUCTION 



III. IRRITABILITY 



Assimilation 

 Growth 

 Dissimilation j 



j Asexual 

 I Sexual 



f Reception of 



Stimuli 

 Transmission 



of Stimuli 

 Coordination 



Movement 



Have no special organs or sys- 

 tems 



Xo special organs or systems 

 Ovaries, Testes, Uterus Genital 



Sense Organs ] 



Nerves } 



Gangalia, Brain j 

 Muscles 



Nervous 



Muscular 



These various organs and systems will be considered in detail in 

 connection with each of the animals studied. 



I. DEVELOPMENT OF OVUM. 



In prepared slides of Echinoderm eggs observe the following 

 stages: i. Cleavage; i-cell, 2-cells, 4-cells, 8-cells, [6-cells, 32- or 

 64-cells. Observe the appearance of a cleavage cavity after the 

 8-cell stage. 



2. Blast nla : Observe the hollow sphere composed of a single 

 layer of cells (Epithelium). Are there any indications that scattered 

 cells (Mesenchyme) migrate into the cavity of the blastula (Blas- 

 tocoel) as in Volvox? 



3. Gastrula: Note the flattening and ultimate infolding of the 

 blastula at one pole. Do the cells at this pole differ in appearance 

 from the others? The infolded cells constitute tin endoderm, the 

 outer layer the ectoderm. The infolded cavity is the Gastrocoel, or 

 digestive cavity ; the opening to the exterior is the Blastopore. 



Draw and label the stages and structures named above. 



