SPONGE WE A VERS. 137 



duction of a bud (gemmule) by independent growth, 

 or by spontaneous division of the sarcodous sub- 

 stance of the sponge." 



Before leaving this portion of the subject, some 

 brief allusion must be made to those bodies which 

 have been denominated " ciliated sponge gemmules " 

 or " ciliated larvae," developmental forms of the 

 " collared ciliated monads," referred to in describing 

 the sarcode or flesh of the sponge structure. Mr. 

 Saville Kent, who is responsible, not only for the 

 name but the character of these forms, says that 

 " the initial condition of these reproductive struc- 

 tures, as conceded unanimously by the independent 

 testimony of every investigator, takes the form of 

 an amcebiform body, varying in size from the three- 

 thousandth to the two-hundredth part of an inch, 

 and presents a considerable likeness to the primary 

 condition of an ordinary ovum, or egg." "These 

 amoeboid oviform bodies are not independent pro- 

 ducts of the adult sponge stock, but simply retro- 

 morphosed collar-bearing zooids that have retreated 

 within the mucous stratum (cytoblastema), and 

 assumed, as is common to them, after passing their 

 matured collar-bearing stage, an amoeboid condition. 

 It is invariably found that these bodies are produced 

 first in the deeper and consequently older portion 

 of the sponge stock. This ciliated reproductive 

 structure is in no sense an egg, or its derivative, but 



