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PACIFIC SCIENCE, Vol. XXII, July 1968 
intercellular connections between collencytes 
are extremely fragile and are readily broken. 
Such connections are not found in smear prep- 
arations. 
As stated, archaeocytes, which also occur in 
relatively large numbers in T. zeteki, are often 
found to include zooxanthellae. It is of interest 
to note that according to McLaughlin and Zahl 
(1966), the terms "zoochlorellae” and "zoo- 
xanthellae” are not generic designations but 
their contemporary meanings are primarily 
coloristic. Zooxanthellae are yellowish to green- 
ish-brown algal cells, while zoochlorellae are 
pale to bright green cells. Those found in T. 
zeteki archaeocytes are yellowish-green and 
therefore are designated as zooxanthellae. 
The occurrence of symbiotic algae, zooxan- 
thellae or zoochlorellae, in sponges has been 
known since the investigations of Weber and 
Weber-van Bosse (1890), Koorders (1902), 
van Trigt (1919), Rodriguez (1930), van 
Weel (1949), and others. The sponge cells 
enclosing such algal cells have been designated 
by a variety of names. As examples, van Weel 
(1949) refers to the cells of Spongilla proli- 
fer ens as "amoebocytes with symbiontic algae” 
(abbreviated "ASA”) and infers that they are 
different from "phagocytes,” and Rodriguez 
(1930) refers to such cells in Spongilla lacus- 
tris Johnston as "amoebocytes.” An examination 
of the descriptions of these host cells has con- 
vinced us that such cells should all be designated 
as archaeocytes in that they all are relatively 
large, are capable of producing lobose pseudo- 
podia, possess prominent nuclei with nucleoli, 
and may include cytoplasmic granules and 
vacuoles. In fact, Pourbaix (1933), in review- 
ing Rodriguez’ work, has referred to these 
cells as archaeocytes. 
It may be significant that symbiotic algal cells 
are found only in archaeocytes and not in other 
types of cells. Our studies on the phagocytic 
roles of the various types of parenchymal cells 
in T. zeteki, which will be published at a later 
date, indicate that archaeocytes are much more 
active and efficient in phagocytizing foreign 
materials. According to Rodriguez, the algal 
cells enter sponges via the flagellated choano- 
cytes and are later transferred to parenchymal 
amoebocytes (= archaeocytes ) . As the result of 
finding algal cells in the process of being di- 
gested within archaeocytes, van Trigt (1919) 
concluded that the relationship between the alga 
and the sponge is not a completely compatible 
one; however, van Weel (1949) has shown that 
sponges, in his case Spongilla proliferens, are 
associated with only one species of alga, in his 
case Pleurococcus vulgaris, thus suggesting spe- 
cificity, and having found few examples of 
intracellular digestion of P. vulgaris, he dis- 
agrees with van Trigt that the relationship is 
not totally compatible. Van Weel is of the 
opinion that only dying or dead algae become 
digested. Our examination of zooxanthellae 
within T. zeteki archaeocytes revealed very few 
instances of intracellular digestion and we tend 
to agree with van Weel that the relationship is 
one of compatible symbiosis, most probably 
mutualism as defined by Cheng (1967). 
The nature of the cytoplasmic inclusions of 
T. zeteki thesocytes remains essentially un- 
known. Our preliminary studies indicate that 
the larger globules do not represent glycogen. 
On the other hand, certain ones give a positive 
test for lipids. It is of interest to note that 
Pourbaix (1934) has reported that the nutrient 
reserves in certain cells comprising the gem- 
mules of Ephydatia fluviatilis Lamouroux are 
not glycogen but may be proteinaceous, prob- 
ably a glycoprotein. In addition, he has found 
unidentified lipoid globules. Similarly, van 
Weel (1949) reported that no glycogen occurs 
in the cells of adult Spongilla proliferens ex- 
cept in ovocytes and that fats occur in what he 
termed "phagocytes.” Our findings confirm the 
presence of lipids and the absence of glycogen 
in the nutrient-storing cells of sponges. Further- 
more, it is possible that those globules which 
do not give a positive stain with either Sudan 
Black B or Lugol’s iodine may represent glyco- 
protein granules. This, however, is pure specu- 
lation and needs histochemical confirmation. 
Our finding of intracellular formation of 
spicules in the few scleroblasts encountered 
indicates that in T. zeteki the spicules are 
formed intracellularly, at least initially, al- 
though the exact machanisms involved remain 
to be determined. 
As we have stated, our interest in the paren- 
chymal cells of sponges stems from inquiries 
into their roles as associated with cellular 
internal defense mechanisms. With the estab- 
