Jekkikos. — Asplanchna. 



PLATE 1. 



Fig. 1. Egg showing the maturation spindle. 



Fig. 2. Egg slightly older than that shown in Figure 1 ; the polar cell is formed 

 and is embedded in tiie egg ; the cleavage nucleus, preceded by the 

 deep aster of the maturation spindle, is moving from the place of 

 polar-cell formation toward the interior of the egg. 



Fig. 3. First cleavage spindle, early stage. 



Fig. 4. Longitudinal section (actual). The two nuclei formed at the first cleav- 

 age are separating; the notch and the granules at the periphery 

 indicate the beginning of the formation of the first cleavage plane. 

 The aster in the anterior (upper) end of the egg has divided, while 

 the opposite aster is still entire. 



Fig. 5. Two-cell stage seen from the dorsal side; the anterior end above. 

 There are two asters in the cell AB", while the aster in CD is 

 still undivided. 



Fig. 6. Two-cell stage, from the dorsal side ; spindles in both blastomeres. 



Fig. 7. View of an eight-cell stage ; optical section through the quadrants B and 

 D, showing the distribution of the yolk granules. Observe the con- 

 centration of granules in the ventral part of d*'^, and the position of 

 the asters in d*-^ and c?*-2. 



