Phylum VIII 



Trochelminthes, Class Rotatoria 



A CULTURE MEDIUM FOR HYDATINA SENTA* 



Josephine C. Ferris, University of Nebraska 



BRING to the boiling point in ioo cc. of water i gram of urea crystals, 

 i gram of dried blood, and i gram of dried ox gall. Filter and add 

 3 cc. of this triple solution to ioo cc. of tap or rain water. This solution 

 is very satisfactory for pedigree cultures of this rotifer in watch glasses if 

 fed on Polytoma cultures. [See p. 6 1.] If the Polytoma is cultured in 

 a bone meal and hay solution it should be washed at least twice by 

 centrifuging and decanting. 



References 



For the culture of Hydatina asplanchna see p. 210. 

 For the culture of Philodina see p. 143. 



Class Gastrotricha 



METHOD OF CULTIVATION FOR THE GASTROTRICHA 



Charles Earl Packard, University of Maine 



MANY specimens of Lepidoderma squamatum were reared in a 

 0.1% malted milk solution for a period of 22 months. 



One half gram of Horlick's malted milk was dissolved in 500 cc. of 

 clear water from a spring-fed river tributary, usually unfiltered, and 

 boiled for 5 minutes. This was left exposed for 24 hours before being 

 used. Sometimes the solution was filtered, though usually not. Ani- 

 mals were raised in rectangular, covered refrigeration dishes in quantity 

 lots and in depression slides singly or in mass. In most cases Lepido- 

 derma squamatum adapted itself readily. When once a culture was 

 started, a small amount of fresh solution was added daily to keep up a 

 supply of animals. Excess fluid was drawn off to prevent overflowing. 



Lepidoderma continuum, and a species of Chaetonotus, a genus char- 

 acterized by cuticular spines, were also raised in the same medium for 

 several weeks, adaptation being less easily accomplished with these forms. 



*See Biol. Bull. 63:442, 1932. 



176 



