306 Dr. L. Orlcy on Nematodes. 



clition just as well out of the body as within it, and that their 

 development is not in tlie least influenced by the latter posi- 

 tion. This rule applies witli greater or less accuracy to the 

 other genera which are grouped with Rhabditiforniffi. Anguil- 

 lula aceti^ it is true, lives in artificially prepared vinegar, but 

 only in the larval state, while it develops sexually and repro- 

 duces only in fermented vinegar. 



Most of the Cephahhi live in roots of moss whicli have more 

 or less undergone decay ; and most lthalKlitida3 live in decom- 

 posing organic matter, or in earth which contains it. We 

 see, then, that it is just as much a necessity for the Ehabditi- 

 formffi to find a resting-place in decomposing matter as it is 

 for the parasitic forms to reach by some means the inside of 

 an animal; while the free-Hving forms, unfettered by such 

 requirements, develop directly under most varied and inde- 

 pendent external conditions. The preservation of tlie species 

 is effected in different ways ; for while the parasites secure 

 this end by producing enormous quantities of ova, with the 

 Ehabditidee, which produce but few eggs, it is managed by 

 tlie constant aggregation of the individuals in large numbers 

 and by tlieir extreiuely rapid development, Avhich occupies 

 sometimes only twenty-four hours ; while their tenacity of 

 life and their habit of wandering gives tliem the power of 

 becoming widely distributed. Home Khabditiforina?, indeed, 

 appear to occur singly ; but this cannot be decided for certain, 

 owing to the imperfect extent to which their habits are known : 

 in cases where isolated individuals are found it is always 

 possible that they may be merely stray members of a colony. 

 It is seldom that the free-living forms live together; they are 

 generally (with the exception of the parasitic Tijlenchi) to be 

 found singly ; they lay very few eggs ; and hence the different 

 s]:)ecies are always found to be feebly represented. Diplogaster 

 riraJis may be mentioned here as showing a transition to the 

 l\habditiforma3 ; for it usually occurs in large numbers in wet 

 ditches among Algw, and also reproduces, as I have often 

 convinced myself, with great rapidity in decayed Algaj. 



Biitschli was the first who endeavoured to unite the genera 

 Oxyuris^ Rliahditis, Ceijlialohus^ and Anguilhda^ on account of 

 their agreement in the structure of the caudal termination in 

 males &c. ; these genera would seem to be closely allied. De 

 Man has placed them in the family " Odontospha^ridai ;" I 

 have called the family Ehabditidaj, De Man associated with 

 them the Plectidie and Diplogasteridse ; but although I 

 cannot deny the close affinity of these forms with the above- 

 mentioned genera, yet they possess so many of the charac- 

 ters requisite to a free existence that we are justified in sepa- 



