36 LABORATORY DIRECTJONS IN 



viduals, which in turn produce asexual individuals. The asexual and 

 sexual individuals are structurally unlike. 



8. Metagenesis in a Colonial Hydroid Obelia. Recall your drawings 

 of Obelia or if you failed before to work out its structure do so at this time. 

 Note especially: 



8a. That the hydranths produce gonangia and hydranths by budding. 



86. That the gonangia produce medusae by budding. 



8c. That the medusas produce hydranths by means of eggs which must 

 be fertilized by spermatozoa. 



Sd. That the kinds of individuals that reproduce asexually are struc- 

 turally very unlike the kind which reproduces sexually. 



Therefore, Obelia exhibits "Alternation of Generations" or "Meta- 

 genesis." 



D. SUMMARY 



The summary should consist of discussions of abiogenesis, and of 

 asexual and sexual reproduction or a comparison of the two modes of 

 reproduction pointing out distinguishing or essential features of each. 



