36 INTRODUCTION TO ZOOLOGY chap, ii 



pond water or clean rain water, and supplied with fresh duck- 

 weed and other water-weed from a pond ; cover the vessel and 

 keep in a light but not a sunny place ; watch the life of the 

 Hydrae, and the formation of new individuals by budding. 



Obtain other species of Hydra and watch them also. 



Examine any colonial Hydroids and medusae that you can 

 obtain,! sketching them carefully and identifying them if possible 

 by reference to such a book as British Hydroid Zoophytes, by T. 

 Hincks (2 vols. 1868). 



' If it is not possible for the student to get these direct from the sea, 

 they can always be obtained from the Marine Biological Laboratory, 

 Plymouth. 



