STRUCTURE AND LIFE-HISTORY OF A SPONGE. 
37 
on the contrary, attached itself by the mouth, which, by subsequent 
growth, became obliterated. Hence the origin of pores, and the 
vent which we conventionally call the mouth. We have already 
stated that some sponges remain their whole life through in the 
simple stage now reached, giving rise to other sponges, which no 
more pass beyond it than their parents did ; yet in the history of the 
sponges, there must have been a time when one of these simple 
Olynthi progressed a step further and produced the additional com- 
plication of radial-tubes. These are simply so many repetitions of 
the young Olynthus budded out from its sides, and thus again we 
have co-operation, a number of young Olynthi, remaining attached 
together to form the wall of the Sycandra. But they all perform 
the same functions ; the succeeding and more important step, the 
acquirement, by some of the tubes, of one set of functions, and by 
others, of another, has not yet taken place ; some day, perhaps it 
may ; the future is infinite with possibility, and Sycandra may even 
yet, be destined to a brilliant and successful career. 
