NOTES ON THE FliEE-LlVING NEMATODES. 485 



attention has not been paid to the part which nematodes play 

 in the economy of the soil/ but an investigation of this 

 problem may well reveal results of as great interest as those 

 which have been pnt on record by Maupas, working on the 

 sexnal organisation. In the present paper it is proposed to 

 confine attention to the reprodnctive phenomena in certain 

 hermaphrodite species, but it is hoped in a subsequent 

 research to return to the nutrition and distribution of the 

 class. 



Cultnres of free-living nematodes in connection with this 

 Avork were first started at the Stazione Zoologica, Naples, in 

 1906, and continued at intervals in the next two years at the 

 Zoological Laboratory, Cambridge, using for the most part 

 Diplogaster linstowi. In 1909 I spent.Julyto September 

 at the Sntton Broad Laboratory, Norfolk, and procured from 

 the neighbonrhood the two forms, Rhabditis gurneyi and 

 Di plogaster maupasi, the study of which enables me to 

 amplify in one or two particulars Maupas' account of the 

 fi-ee-living hermaphrodite species of nematodes. I wish here 

 to express my sense of the value of the opportunities for 

 research afforded l)y the Sutton Broad Laboratory, and to 

 thank Mr. Robert Gurney for his great kindness to me while 

 woi'kiiig there. 



Summary of Sexual Phenomena in the Hermaphrodite 



Species. 



Guido Sclineidei', in his 'Monographic der Nematouen' 

 (1860), fii-st discovt'it'd and put beyond doubt the existence of 

 self-lertilisnig hei-maphrodiie species of free-living nematodes. 



^ The importance of the protozoan fauna of soil has but recently 

 been realised. Like that of the nematodes their nutrition is composed 

 of bacteria, and the place they take as a limiting factor in the increase 

 of nitrifying forms has the closest possible bearing on the fertility of 

 the soils they inhabit. It is, however, probable that these protozoa are 

 more widely distributed in soil and so exercise a more important 

 influence. (See E. J. Russell and H. B. Hutchinson, ' Journ. Agric. 

 Sci.,' vol. iii. 1909, '• The Effect of Partial Sterilisation of Soil in the 

 Production of Plant Food," especially p. 141.) 



