THE CONTINUOUSLY ZOOIDAL 81 



zooidal but discontinuous. And there are even objections to 

 classifying all Hydrozoal colonies as Continuously Zooidal ; 

 for there are numerous examples which, while they may be 

 so described as regards their vegetative or asexual structure, 

 nevertheless manifest a higher form of Continuity in their 

 sexual parts. Some Hydrozoal colonies are zooidal through- 

 out, and their sexual organs are just zooids specially adapted 

 for producing sexual elements, and in these types the whole 

 colony may be said to exhibit Serial Zooidal Continuity. 

 But there are others which, while serially zooidal in vegetative 

 structure, exhibit in their sexual structure a " multiplication " 

 of the serial into Lateral Continuity, with the result that the 

 Individual is partly zooidal and partly " megazooidal." 

 This is a new term to be explained presently when we come 

 to Individuals which are wholly " megazooidal," but it 

 may be said here that the sexual megazooid of Hydrozoa 

 is another example of the " terminal compression " connected 

 with reproduction. It has already been mentioned in the 

 case of the higher Fungi, where it results in the production of 

 " false tissue." Just as the Continuity of the false tissue is 

 a multiplication of that of the loose mycelium, so is the 

 sexual megazooid's a multiplication of zooidal Continuity. 

 It may also be remarked that amongst Hydrozoa there are 

 commonly included the large Individual Medusae, or Jelly- 

 fish, which directly reproduce themselves as Medusae. These 

 are not in any sense Continuously Zooidal Individuals ; 

 they are wholly Megazooidal. 



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