RESISTANCE OF RHABDITIS TO ACIDS. 



HIKOKL'RO HON'DA. 

 DEPARTMENT OF ZOOLOGY. UNIVERSITY OF PENNSYLVANIA. 



As is well known, Anguillula aceti lives in vineger and is highly 

 resistant to acetic acid. Henneberg (i) has shown that this 

 nematode can live in 13.5 {>er cent, acetic acid. Abbott ami 

 Richards have reported that it can live for more than 24 hours in 

 Tellyesnicky's fluid, and for three or four hours in GilsonV fluid. 



The writer intended to see in the first place whether other 

 free-living nematodes, which do not come in contact with -u - ; .<l- 

 in their natural life, were resistant particularly to acetic arid as 

 well as other acids. For this purpose Rhabditis elegans was ch< ui. 

 In the course of the work it was found that Rhabditis is ni<>n 

 resistant than the tadpole, Daphnia, Aehsoma, and Paramecinm 

 not only to various kinds of acids, but to other toxic substanrr- 

 as well. The cuticle with which nematodes are covered is known 

 lo be composed of a very resistant substance; experiments, 

 therefore, were tried to determine whether or not the cuticle is 

 responsible for this resistance, the worms, injured and uninjim <l, 

 being stained in solutions of neutral red and of methylene blur. 

 'This work w.is begun at the suggestion of Dr. M. II. Jacobs, 

 whom the writer wishes to thank for valuable advice. 



Adult hermaphrodites of Rhabditis elegans and tadpolr> about 

 io mm. long and with external gills were used. R. dc^nn\ i- 

 found in decayed matter and is easily cultivated in a prptonr 

 solution. Every experiment was repeated at lr.i-t twirr. .uul 

 14 to 30 individuals were used for each experimmt. The tem- 

 perature at which experiments were dour varied fnnii 21* C. i<> 

 26 C. 



As shown in Table I., Rhabditis is the IDOM rcH-t.int to \.irious 

 kinds of acids. It might be noted that it can li\r about two hours 

 in N/3O acetic acid, while Daphnia, the form next in order of 

 resistance, can live only about an hour and a <|u.irirr in N/ioo 

 acetic acid. From the results of the experiment- -iven in the 

 lable we notice, however, that Rhabditis i- not particularly 

 n>i>tant to acetic acid as comparrd with othrr acids. 



