17 



all over the body in the parenchyma, so among the meso- 

 gloea (intercellular substance, ground subst. ') ). (As for their great 

 importance in sponge life, see Weltner (1. c.) and Minchin (45) 

 p. 57 — 60). The green colour grains are mostly lying free in 

 the protoplasm (of the amoebocytes), only seldom in a vacuole. 

 In fig. 4 such an amoebocyte is represented in the form I so 

 often observed, when wholly isolated from the sponge-tissue and 

 attached to the coverglass in my living preparations of tissue. 

 It then seemed entirely „vacuolized". However, I don't think 

 these open spaces to be real vacuoles belonging to the cell. (See 

 Appendix, III). 



Besides in these amoebocytes, the green corpuscles also occur 

 — but much less numerous — in the pinacocytes of the inner 

 and outer surface of the sponge body, in the choanocytes of the 

 flagellated chambers, and finally in the intercellular groundsubstance. 



II. The behaviour of the green colouring-matter. 



We now have to examine of what the green corpuscles of the 

 sponge cells consist; in other words, we have to prove that the 

 material of jvhich the corpuscles consist is morphologically and 

 physiologically identical to the chlorophyll, that we know from 

 the plants. Sorby (54), Lankester (35) and Brandt (8) have 

 already studied this problem. Sorby and Brandt compared the 

 spectra of solutions of the green sponge colour, obtained in dif- 

 ferent ways, with the corresponding solutions of vegetable chlo- 

 rophyll ; in this way the identity of the spectra was stated. 

 Lankester compared the structure ; and concluded, that the simi- 

 litude in form and structure proves the absolute identity of the 

 green corpuscles of the sponges to that of the plants. 



As regards the physiological identity^ we don't possess any deci- 

 sive proofs at all ; though this only should give the decision ! In 

 the first place we have to show that the green corpuscles pro- 

 duce Oo when exposed to light, and in the second place, that in 



1) For this, see Appendix, I. 



