171 



incurrent canal, transports them immediately to an excurrent one, 

 to eject them. I specially think of the case of Fig. 73 (supposed 

 that the plasmic layer outside and against the flagellated chamber 

 also belongs to an amoeboid cell). Even, with the existing dimen- 

 sions it would be possible, that one single amoeboid cell extends 

 as well at the outside (incurrent canal side) of the flagellated cham- 

 ber as near the apopyle; this cell, in other words, would be able 

 (without getting out of its place) to take the carmine from the 

 incurrent canal and eject it into the excurrent one, by simple 

 protoplasm current within its own body. A very simple and 

 rapid process! 



F. APPENDIX. 



Some separate observations '). 



I. 



First I want to speak about the often mentioned (p. 17, 146 — 148, 

 150—154, 156, 163, 166, 168—170) undifferentiated intercelhday 

 plasmic substance {ground-substance^ mesogloea). 



As is generally accepted, the tissue mass, which occurs in the 

 sponges between the pinacocytic epithelium of outer and inner 

 surface and the choanocytic layers of the flagellated chambers, 

 the so called parenchyma , consists of ground-substance with 

 cells. MiNCHiN (45) says about it: „The skeletogenous stratum 

 (parenchyma) is developed to a very variable extent in different 

 sponges. Scarcely recognisable in some, in others it attains great 

 proportions, making up all but a relatively insignificant portion 

 of the total bulk of the sponge body. It consists of a gelatinous 

 ground-substance or mesogloea, which contains cells of various 

 kinds. The mesogloea is the first portion to appear as a struc- 

 tureless layer between the dermal and gastral epithelia, and is 



1) Here should have foUoweJ a description of a remarkable phenomenon in living 

 gemmule cells of Spongilla; however, I have meanwhile published this elsewhere 

 (VAN Trigt, 57 c). 



