MOLLUSC01DA. SOS 



some strong breeze. Unhappy, indeed, is the fate of the unfortunate 

 infusoria which chance leads at this moment into the fatal circle. 



In many species, observers have discovered a special organ called 

 the vibracule, which deserves our attention for a moment. It is a 

 hollow filament, situated at the upper and outer angle of each cell, 

 filled with a substance which is at once fibrous and contractile, ad- 

 mitting of some very remarkable movements, which occur regularly, 

 and generally at very short intervals. At first the filament inclines 

 itself towards the base, trembles, oscillates, and seems to sink ; pre- 

 sently it recovers itself, and inclines in the opposite direction, where it 

 repeats the same operation with the same order and in the same time. 

 " What are the functions thus performed ?" asks Fredol. " Are they, 

 we would ask, independent up to a certain point of the will of the 

 Bryozoaire ? What is their purpose ?" We think he answers, " That 

 this organ serves the purpose of cleansing, and especially that of 

 strengthening, the entrance to the cell. It even continues its move- 

 ment after the animal has been mutilated or killed. The poor sickly 

 or dead creature continues to be defended by its protecting vibracule." 



The prey which is drawn into the vortex by the tentacles and their 

 appendages enters into the mouth, to which is attached a pharynx, 

 oesophagus, stomach, and intestines. In the back or haemal region, 

 not far from the mouth, there is a special opening for this intestine. 



Eespiration is provided for in the Bryozoaires by the ciliate appen- 

 dages which surround the mouth ; they are at once tentacula and 

 branchiae. The animal presents no other trace of organs of the 

 senses. A small ganglion and a few fillets constitute all of the nervous 

 system which can be traced ; neither heart nor blood-vessels have been 

 found. 



The egg, in the case of the Bryozoaires, gives birth to a young 

 animal covered with hairs on its surface ; it swims about freely until it 

 has chosen a convenient place in which it can establish the new colony 

 which it is to originate. But this choice is not made for itself alone ; 

 the young animal encloses under its hairy envelope two new indi- 

 viduals, which, young as they are, have already the appearance of 

 adult Bryozoaires. At first, these only increase the number of the 

 colony by budding, but in a short time they produce eggs. 



From these remarks it will be seen that the animals of the 

 Bryozoaires are more complex in their form and functions than those 



