THE FORMATION OF NEW COLONIES OF THE 

 ROTIFER, MEGALOTROCHA ALBO- 

 FLAV1CANS, EHR. 



FRANK M. SURFACE. 



Colony formation is not common among the Rotifera. But in 

 several species, belonging especially to the family Melicertidje, 

 the individuals do become aggregated into colonies. These 

 animals do not reproduce by budding, as do so many colonial 

 forms, nor in most cases does the colony contain the progeny of 

 its members. Instead, the young are hatched as free swimming 

 individuals which later become segregated into a separate fixed 

 colony. 



During the past winter, while a graduate student at the Uni- 

 versity of Pennsylvania, the writer made some observations on 

 the formation of new colonies of Megalotrocha alboflavicans. 

 Colonies of this large rotifer were found in abundance in the fresh- 

 water tanks of the vivarium, whither they had been transferred 

 some years before from the small pond in the botanical gardens. 

 These colonies are ordinarily formed on the roots and stems of 

 various water plants, but in the vivarium they were found only 

 on the stems of Myriophyllum, The colonies are nearly spherical 

 in shape and when adult may measure as much as 4 mm. in 

 diameter. They are thus easily recognizable to the unaided eye, 

 appearing as white spots on the dark or green stems. The 

 colonies used were kept in glass jars in the laboratory and for 

 observation a piece of the stem containing a colony, was 

 removed, placed in a small dish and observed with a Braus- 

 Driiner binocular. 



The work was undertaken at the suggestion of Professor E. G. 

 Conklin, and it is a great pleasure to acknowledge my indebted- 

 ness to both him and Professor H. S. Jennings for their many 

 valuable suggestions and kindly criticisms. 



The colonies of Megalotrocha are not surrounded by gelatinous 

 masses or tubes as are certain other species of the Melicertidae. 



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