PORIFERA, CQELENTERATA, VERTEBRATA 71 
TaBLE OF THE Various CLaAssEs OF CELLS IN SPONGES 
1. Pinacocytes 
(epithelial cells) 
2. Myocytes 
I. Epithelial stratum (contractile 
cells) 
. Gland cells 
. Spongoblasts 
. Pore cells 
. Scleroblasts 
. Collencytes 
III. Skeletogenous (stellate cells) 
stratum 8. Desmacytes 
(fiber cells) 
9. Cystencytes 
(bladder cells) 
Gastral Layer IV. Gastral epithelium ; 10. Choanocytes 
(collar cells) 
11. Phagocytes 
(ingestive cells) 
12. Trophocytes 
(nutritive cells) 
. Thesocytes 
(storage cells) 
. Statocytes 
(gemmule cells) 
. Gonocytes 
(sexual cells) 
Dermal Layer; II. Porocytes f 
~E OD Or He 09 
V. Amebocytes (wan- 
Archzeocytes dering cells) 13 
(primordial 
cells) 14 
VI. Tokocytes (repro- 15 
ductive cells) 
blastula-like larva is formed (Fig. 27, A). At the 
posterior pole two blastomeres (posterior granu- 
lar cells, p.g.c.) remain undifferentiated; they are 
much larger than the other cells, are granular, and 
possess vesicular nuclei. The larva becomes fixed 
by the anterior pole, and during the metamorphosis 
that then takes place, the two posterior granular 
cells, the archeocytes, multiply rapidly, forming a 
large number of minute cells which resemble certain 
leucocytes. These are known as amebocytes. By 
