199 



Table 6. The )n()iiher of tJie various (p'een and colourlc.'is clilo- 

 wpliyll corpuscles present in different stages of development of the 

 tissue of living green and colourless Spongillidae grouni in light or 

 in darkness, examined microscopically by means of ravel preparations 

 of the tissues (pag. 12 — 14). 



It was of much importance to know tlie intrinsic amount of chloro- 

 phyll corpuscles in the sponge tissue during its different stages of 

 development, viz. in its prime youth — when growing vigorously — , 

 in full-grown state — growing no more — , and in its stage of rest — 

 as gemmulae in winter. Young, growing tissue we find 1^' in the small 

 (2 — 5 m.M.) sponge-disks, attached for instance to stones, and being 

 probably newly germinated gemmules ; 2'"! in the tops of tlie branches 

 of Spongilla (p. 16); probably, however, the disks will appear younger 

 than the tops. Full-grown tissue we generally find all over the sponge 

 body except in the tops, so for instance at the base of the branches 

 or in the crust (p. 16). This only concerns Spongilla; as mentioned 

 (p. 16), Ephydatia does not form long branches but cushions; so in 

 this sponge we can not distinguish a certain limited region of growth. 

 There the growth is more general, but then locally not so vigorous 

 as it is in the tops of Spongilla. 



Consequently, for Spongilla I shall indicate in the table the amount 

 of chlorophyll corpuscles in 4 groups, viz. for the tissue of l^' sponge- 

 disks, 2°'i branch-tops, S'"! branch-bases or crusts, ¥^ gemmules. In this 

 last group one may distinguish again the gemmules in different 

 stages of development; their last stage then joins the group of the 

 sponge-disks. In this way the circle is accomplished. For Ephydatia 

 we can not give groups of old and young tissue — as mentioned — ; 

 of course it could be done for disks and gemmules, but this has been 

 left out here. 



In the tables is indicated: ((. The month of the analysis of each 



