THE COASTS OF SICILY. 229 



was especially distinguished for the success with which 

 he was enabled to arrive at great results through 

 the observation of minute phenomena, that under 

 the influence of certain circumstances, a well cha- 

 racterised mucedina may produce an agaricus, which 

 at first sight seems as remarkable as if we were to 

 see an oak sprouting from a bramble. 



Here the resemblance to the Medusae is most 

 remarkable. From the bands, which are disposed 

 under the head of the mushroom, a spore or re- 

 productive body is discharged ; in the same manner 

 as in the Medusae, the ovary, which is placed below 

 the umbrella, throws off an ovum which becomes 

 converted into a ciliated larva. This larva, attaching 

 itself to some substance, produces a polypary, in the 

 same manner as the spore through its development 

 gives birth to a mycelium. This product, if sub- 

 jected to certain conditions, will maintain its original 

 form, and will merely throw off branches in the same 

 manner as the polypary will produce polypes. Both 

 may, moreover, be reproduced under this form, either 



capillary action, or to imbibition. Although these explanations 

 were found to be incomplete and vague, no better ones had as yet 

 been offered. M. Dutrochet now showed that when two liquids 

 differing in nature and in density are separated from one another 

 by a thin membrane, there is developed in this membrane a special 

 force, which causes one of the liquids to pass through it ; and he 

 further showed that this phenomenon continues until the equilibrium 

 is more or less completely reestablished between the liquids which 

 bathe the two sides of the membrane. He called this force 

 endosmose when it caused the liquid to flow into the apparatus which 

 served for his experiments, and exosmose when it tended to expel 

 it. Fundamentally, however, these forces are identical, and they 

 may both be designated under the n ame of endosmose. 

 Q 3 



