78 GENERAL BIOLOGY 



or distributed in any special relation to light? Note where 

 the specimens are most abundant, rotate the jar 90 to 

 180 degrees and observe again after several days. Have 

 the hydras retained the old position or are they in a new 

 part of the jar? Are they in the same position, relative 

 to the source of light, that they were before the jar was 

 moved? 



5. Food Taking. It is possible to artificially feed specimens 

 by suspending bits of raw beef within reach of the tentacles, 

 or by placing it in watch glasses with hydra. The method 

 of capturing prey may often be observed by placing water- 

 fleas in a jar or watch glass containing hydra. 



6. Reproduction. (a) Asexual. The presence of buds 

 has already been noted. How does the process take place? 

 In what ways does it differ from the process of fission in the 

 protozoa? What becomes of the bud? What parts of 

 the body are involved in the formation of the bud? Draw T . 



(6) Sexual. The same individual usually produces both 

 male and female reproductive products. The spermaries 

 (testes or male organs) will be found, if present, as small 

 conical elevations on the body just below the tentacles. 

 If these are mature the microscope may show active move- 

 ments on the inside; this is caused by the swimming of the 

 spermatozoa within the testis. If the testis is ruptured the 

 spermatozoa may be seen swimming about in the water. 

 Is there more than a single testis on one animal? 



The ovaries (egg-producing or female organs) usually 

 develop later than the testes and will therefore not be found 

 on the same animal that shows the male organs. The ovaries 

 are larger than the testes, more spherical, and occur near 

 the base of the animal. Within the ovary may sometimes 

 be seen the single large egg or ovum. Is there more than a 

 single ovary on one animal? 



