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A New Method for Growing Hydroids in Small Aquaria 

 by means of a Continuous Current Tube. 



By 

 Edward T. Browne. 



(University College, London.) 



With one Figure in the Text. 



The simple piece of apparatus, to which I give the name " Current- 

 tube " was made last year in the Marine Laboratory at Plymouth. I 

 designed it especially for growing Hydroids, and for them it has proved 

 to be a success ; but it should also be useful for other fixed organisms, 

 such as sponges, polyzoa, and ascidians. 



The previous methods which I had used for growing Hydroids in 

 bell-jars or small aquaria never gave complete satisfaction. Occa- 

 sionally a success was recorded, but there were too many failures, 

 which frequently involved a great waste of labour. 



A Hydroid colony when it has an ample food supply grows at an 

 astonishingly rapid rate. I will give as an example of this the growth 

 of Syncoryne eximia in one of my bell-jars at Plymouth in Sep- 

 tember, 1897. 



The colony was taken on September 14th, and suspended in a bell- 

 jar with one of its branches touching the glass. This branch sent out 

 a shoot which attached itself to the glass and became converted into a 

 stolon. The growth of the stolon and its lateral stolons or branches 

 was measured and sketched daily from September 18th to 23rd, and 

 on the 27th. 



On September 18th the stolon was 14 mm. in length and had no 

 lateral branches. Nine days later (September 27th) the main stolon 

 measured 77 mm. in length, and its numerous lateral stolons or 

 branches measured altogether 500 mm. These measurements ex- 

 cluded the short stalks of the hydranths, which were then seventy- 

 seven in number. During the same period a second stolon came off 

 from the old colony, and on September 27th it measured 70 mm. in 



