RESTITUTION-BODIES AND FREE TISSUE-CULTURE IN SYCON 321 
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etc.’, ‘ Festschr. fiir R. Hertwig ’, 1910, Bd. 3. 
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i. (1910).—** Beobachtungen iiber Reduktionsvorgiinge bei Spongil- 
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= 
ae 
EXPLANATION OF PLATES 13 AND 14. 
The figures are all drawn from life with the Abbé camera lucida. 
The magnifications are given as follows: 8+40c., denotes 
drawn at table level with a no. 8 (4”) objective and no. 4 
Huyghenian ocular. The objectives and oculars were Reichert 
unless otherwise stated. 
PLATE 13. 
Fig. 1.—A subdivided restitution-mass. (Eight days.) a. The whole 
mass. The spherules are mutually compressed and show a definite cubical 
epithelium. (3+40c.) 6. A single spherule under higher power. The 
central mass is distinct from the epithelium. (6+ 2 oc.) 
Fig. 2.—Different stages of another subdivided mass. (3+4 0c.) 
a. A nine-day mass. The spherules have separate gelatinous layers, and 
no sharp epithelia, Dark areas are seen within them. 6b. Three days later, 
All but one possess well-marked dermal epithelia and have somewhat 
expanded. The central masses are irregular, and several have fragmented. 
Fig. 3.—A small eleven-day mass with dermal epithelium ; the contents 
are subdivided into small spherules. No jelly-layer. (3+4 oc.) 
Fig. 4.—Ten-day subdivided masses. The individual jelly-layers of 
the spherules are not shown. (3+4 oc.) 
Fig. 5.—A single spherule of the mass of fig. 4, three days later, under 
higher magnification, The layer of jelly, the separation of the clear cells, and 
