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PLATE III. Disturbance of the structure of the egg by centri- 

 fuging. Egg of a snail, Limnaea stagnalis, centrifuged before the 

 beginning of cleavage, i : Cap of fat with large vacuoles at tne 

 centripetal pole. 2: clear cytoplasm with few inclusions. 3: zone 

 of mitochondria. 4: centrifugal cap containing the protein yolk. 

 The animal pole is at the right, with the egg nucleus (e.n.) and 

 the two polar bodies (l.p.b. and 2.p,b.). 



