Defense Mechanisms of Sponges, I — Cheng et al. 
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m 
Figs. 1-18. Cell types found in the parenchyma of Terpios zeteki. Drawn from living material. 
1-5. Collencytes. Notice the fine filament-like pseudopod in 4 and the dividing collencyte in 5. (Scale A) 
6-11. Archaeocytes. Notice the presence of a symbiotic zooxanthella (a) in 7-10, the formation of pseu- 
dopods in 9 and 10, and a dividing cell in 11. (Scale B) 
12-14. Thesocytes. Notice two types of cytoplasmic inclusions, the larger bodies (r), and extremely small 
granules. (Scale C) 
15. Scleroblast. Notice the intracytoplasmically developing spicule (ds) . (Scale D) 
16-18. Chromocytes. Notice the pigment granules ( pg ) in all the cells depicted and the formation of 
a pseudopod in 18. (Scale E) 
