BY R. VON LENDENFELD, PH.D. 981 



I have met with the elements I refer to in the Syconidje, around 

 the regularly disposed pores in the dermal layer. Here we find 

 circular spindle-shaped cells, which form a contractile sphincter by 

 the aid of which the pores can be more or less closed. In Lencones 

 which have extensive Sub-dermal cavities there are longitudinal 

 cells of this kind in the pillars which connect the outer membrane 

 with the body of the Sponge. 



AMCEBOID CELLS. 



I have met with these elements in all calcareous Sponges. They 

 represent like those of other Sponges, the lobate Amcebse, and 

 move about pretty rapidly in the Gallert. I have not observed 

 that they are packed more closely together in one part of the 

 Sponge than in another. 



They seem equally distributed. Their number is subject to great 



variations. I have always found more in Lencones than in other 



Sponges. 



SEXUAL PRODUCTS. 



The ova are transformed Amoeboid cells which are when 

 matured, enclosed by an Endothel. Before that they creep about, 

 and are distinguished by their size and granular Protoplasm from 

 ordinary wandering cells a long time before they become sessile and 

 enclosed by Mesodermal pavement cells and so surrounded by a 

 Follicula. 



Genei*ally four or five ova lie together in separate Follicula 

 closely packed together and surrounded by a common Follicula in 

 the Heteroccelia. In the Homoccela the ova remain simple and no 

 Follicula is formed as in their higher developed relations, although 

 also here the indifferent star-shaped cells congregate around the ripe 

 ova. 



The first stages of development are passed through within the 

 body of the mother. 



The Spermatozoa are formed in numbers within transformed 

 Amoeboid wandering cells, Spermospores, which betray their 

 nature a long time before Spermatozoa begin to make their appear- 

 ance as small dots ; the nuclei are derived from the nucleus of 

 the Spermospore by continued fission. 



