GONIONEMUS, TUBULARIA 51 



Murbach: The Static Function in Gonionemus. Am. Jour. Physiol., 

 10, 1903. 



Perkins: The Development of Gonionema murbachii. Proc. Acad. Nat. 

 Sci., Phila., 1902. 



: Gonionemus, Science, 1926, p. 93. 



Yerkes: A Study of the Reaction of the Medusa Gonionema mur- 

 bachii to Photic Stimuli. Am. Jour. Physiol., 9, 1903. 



TUBULARIA (Parypha) 



This form is frequently abundant on the piles of old 

 wharfs and on rocks, where the colored colonies form con- 

 spicuous masses just below low-water mark. 



Examine the general form of a colony and note, either 

 with a hand lens or with the naked eye, the stem, or hydro- 

 caulus, as it arises from the branching, matted hydrorhizal 

 portion of the colony. The parts of the colony will be seen 

 to differ from the Leptomedusan (Campanularian) form 

 studied, especially in branching, rigidity, hydrothecae, and 

 gonosomes. 



Make a drawing to show the formation of the colony. 



1. How does a hydranth differ from the hydranth of 

 Obelia in the matter of tentacles? Is a hydrotheca present? 



2. The mouth is terminal and is situated at the end of a 

 proboscis. 



3. The short but rather large body of the hydranth passes 

 back to the perisarc as the fleshy axis, coenosarc. 



4. Notice the gonosomes between the rows of tentacles. 

 What is their origin and arrangement? This is a form in 

 which the medusae are not set free, but remain vestigial. 

 They show neither radiating nor circular canals. The gonads 

 ripen on the partially developed manubrium of the medusa. 

 The sexes are separate. 



Make a drawing of a hydranth. 



5. The male gonophores when nearly mature are rounded 

 or elongated with the space apparently between the man- 

 ubrium and subumbrellar surface filled with sperm. In fact, 

 the sperm are enclosed between the ectoderm and endoderm 

 of the manubrium, but the ectoderm is pressed over against 



