Vol. 5, p. 203-206. June 7, 1926. 



Occasional Papers 



OF THE 



Boston Society of Natural History. 



NOTES ON GEMMULES AND SPICULES IN HETEROMEYENIA 

 RYDERI POTTS. 



BY MILTON F. CROWELL. 



Heteromeyenia ryderi Potts is the commonest sponge found in 

 the fresh waters near the University of New Hampshire, Durham, 

 N. H. The writer has collected sponges from this locality, off 

 and on, during the last three and a half years, and from his 

 collections has found one or two things which seemed to him 

 worthy of record. 



Occurrence of Gemmules. 



The formation of gemmules in the Spongillidae has been as- 

 sumed by many to be a protective habit acquired by the sponge to 

 insure the survival of the species through the cold season of a 

 northern winter, or through periodic dry seasons, as in the tropics. 

 While it seems to be generally true that the gemmules do insure 

 survival through periods of adverse conditions, gemmules are 

 formed, sometimes, in response to other conditions than cold or 

 drouth. 



In the writer's collecting he has taken gemmule-bearing speci- 

 mens of Heteromeyenia ryderi Potts on August 10 and on Feb- 

 ruary 1. Both specimens were taken from the Oyster River, 

 about a mile from the administration building of the University of 

 New Hampshire, and they were taken within 100 feet of each 

 other. On February 1 spongillids not bearing gemmules were also 

 taken. 



Since the Oyster River never goes dry at this point, and since 

 the gemmule-bearing specimen found on August 10 was taken 

 from a pebble from the bottom of the stream, the gemmules could 

 hardly have been formed for the purpose of carrying the sponge 

 through a dry spell, because no dry spell was coming. 



By February 1, 1926, when the specimen bearing gemmules was 

 found, the river had been frozen over for weeks, except in a few 

 open spaces left because of the rapidity of the current. 



The sponge was growing on the under side of a pebble picked 

 from the bottom of the river where the water was flowing rapidly. 

 The animal appeared perfectly healthy and vigorous. It was 

 brought to the laboratory, and microscope slides prepared from it 

 for the purpose of identification. Microscopic examination 

 showed that the sponge was in good condition. The skeleton 

 spicules, while largely mature, showed many that were not fully 

 developed, giving evidence that this specimen was still growing 

 at the time of collection. 



Gemmule-bearing specimens of Heteromeyenia ryderi Potts have 



