SPONGILLA. 551 



were kept under observation, althovigh the true ova of the Spon- 

 gilla, in the same vessel, were growing and spreading vigorous- 

 ly. But the subsequent experiments of Dutrochet, Gervais, and 

 Mr John Hogg, leave no doubt of the truly seminal character 

 of the sphaerulas, — their granular contents contributing to the in- 

 crease of the original mass when they ai"e shed in it, and when 

 retained until the sphserula has been separated by decomposition 

 or maturity, they then give origin to new individuals. The pro- 

 gress of their developement has been well described by my friend 

 Mr Hogg. " Having taken," he says, " many of these fresh 

 seed-like bodies from their fixed localities in the cells or pores 

 of the sponge, I deposited them in a china dish nearly filled with 

 water, which I renewed twice a-day. I was most attentive in 

 examining, not only with my naked eye, but also with a power- 

 ful lens, whether these bodies possessed any spontaneous mo- 

 tions, but could not discover the least appearance of any ; on 

 the contrary, the instant they were put into the water they sunk 

 to the bottom of the dish ; there remaining motionless, most of 

 them commenced to genninate, and became permanently fixed. 

 Several of these seed-like bodies being of different sizes, I found 

 that some began to grow sooner than others, probably by rea- 

 son of their being in a more mature state. The manner of ger- 

 mination, according to my observation, is this : when the seed- 

 like body has lain a sufficient time in the water, a very small 

 quantity of a soft opake substance appears spontaneously pro- 

 truding from its apex or orifice at its top ; it is of a pure white 

 colour, and soon glues the seed-like body to the dish ; this sub- 

 stance gradually increases, and sometimes entirely enveloping 

 the parent body, continues spreading over whatever object it has 

 attached itself to. At first there are no distinct traces of the 

 sponge itself, but only a white tliick gelatinous matter, like a 

 piece of wet cotton wool, is all that is to be seen : this, however, 

 when allowed to drv, will exhibit the thin membrane of the 



