199 



Tarlk 6. The mniihcr of Ihc. rarious giweil end coloiirh^ss clilo- 

 rapln/ll corpuscles present in <li(]ere)if stafjes of devetopnieiit of tin; 

 tissue of Uring green and eolourless Spongillidae groiv)i in Jight or 

 in darkness^ examined microscopically by means of ravel preparations 

 of the tissues (pag. l'i — 14). 



It was of much importance to know tlie intrinsic aiuount of cliloio- 

 phyll corpuscles in the sponge tissue during its different stages of 

 development, viz. in its [trime youth — when growing vigorously — , 

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

 as gemmuhie in winter. Young, growing tissue we ünd 1^' in the sniall 

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

 probably newly gerniinated gemniules; 2'"! in the tops of the branches 

 of Spongilla (p. 1(3); probably, however, tlie disks will ap})ear younger 

 than the tops. FuU-grown tissue we generally lind all over tlie sponge 

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

 or in the crust (p. 46). This only concerns Spongilla; as mentioned 

 (p. iG), Ephydatia does not forin long l^ranches 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 sliali indicate in the table the amount 

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

 disks, 2"'! branch-tops, S"""! branch-bases or crusts, 4*'' gemmules. In this 

 last group one may distinguish again the gemmules in difierent 

 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 lias been 

 left out here. 



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



