cles of food, enter through the system of mouths, and when the food 

 is absorbed by -the cells of the inner lining, they pass out through 

 the larger openings. Both the larger and smaller "mouths" are 

 capable of opening and closing. 



The eggs and sperm cells are scattered at irregular intervals 

 among the cells composing the body-walls ; the spermatozoa are 



in some species developed in "mother" cells, as in many of the 

 higher animals. 



The sponges are by Ha?ckel regarded as closely allied to the 

 Hydroid polypes, members of the Ccelenterates, a division formed 

 by Leuckart, including the polypes and acalephs. His reasons 

 are based on the fact that the sponges are made up of two layers 

 of cells (ectoderm and entoderm, or outer and inner layer) sur- 

 rounding a central cavity, and that both reproduce by eggs and 

 spermatozoa, and pass through a "planula" stage. 



