1071 



MiNCHiN considers that in tiie simplest forms of sponges the choano- 

 rytes would be the principal '"eating organs" ; whilst, according as 

 we observe sponges with a more complicate canalsystem, we see 

 tills function of ingestion performed more and more by the cells of 

 the canal wall, especially in the case of» food-particles too large to be 

 absorbed by the collar cells. It is further self-evident that also the 

 method by which the particles are caught by the collar cells, was 

 conceived in complete agreement with the theory of the water-move- 

 ment, put forwai'd by Vosmaer and Pekelharing. Thus these investi- 

 gators sa}^ that the flagella, by means of the Avhirling movement 

 they produce in the water of the flagellated chambers, secure that 

 the food-particles come as much as possible into the collars of the 

 choanocytes, where they then can be taken up by the protoplasm. 

 Now, since I had been able to state in my normally living 

 preparations a mode of motion of the flagella and the water inside the 

 flagellated chambers wholly different from that described by the 

 latter investigators, the way along which the choanocytes take up the 

 food-particles was also bound to prove wholly different. These particles 

 are not at all taken up inside the collars, but rather outside and between 

 the collars (especially at their base) or between the bodies of the 

 choanocytes themselves; exactly, therefore, in the way known for 



Fig. 3. The capture of (food) particles within a flagellated chamber 

 with 2 prosopyles, namely at the base between the collars 

 of the choanocytes. The path taken by the particles is 

 indicated by dots. The individual cells in the choanocytes- 

 layer (ch.l.) are not drawn: the layer contains numerous 

 particles that have been captured. (Magnification about 

 1000 times). 



74* 



