ORGANS OF SPECIAL SENSE OF PRORHYNCHUS 

 APPLANATUS KENNEL 



WM. A. KEPNER AND W. H. TALIAFERRO^ 



University of Virginia 



THREE TEXT-FIGURES AND TWO PLATES 



This gregarious rhabdocoele was found in the ponds in the 

 vicinity of the University of Virginia. These animals occurred 

 on plants and other submerged objects, especially at the outlets 

 of the ponds where there was a quantity of moss which was kept 

 damp by the falling of the water. These animals are creatures 

 of a crawling habit and never seem to leave the surface of some 

 object. In the laboratory they crawl along the bottom or sides 

 of the aquaria or some submerged surface and never leave this 

 unless forced to do so by some mechanical means. Later in this 

 paper we will point out what we think to be a correlation between 

 the disposition of the organs of special sense in a creeping form 

 like this as compared with the disposition of such organs in a 

 free swimming form such as Microstoma caudatum Leidy. 



Specimens used for this histological study have been fixed in 

 aceto sublimate, at various temperatures, Bouin's fluid, Carnoy's 

 fluid, chrom-formalin mixture, and chrom-aceto-formalin mix- 

 ture. Without exception, we find that the last named fixative 

 is the best for this purpose. Specimens were fixed in this chrom- 

 aceto-formalin mixture- from twenty to thirty minutes, washed 

 in several changes of tap water, and then carried through to 

 paraffin. We find that it is best to handle the specimens sepa- 

 rately and not to work on a large number at one time. Sections, 

 3 to 10 microns thick, were stained in iron haematoxylin with 



1 The authors are mutually responsible for the observations and deductions 

 recorded in this paper. 



2 16 parts 1 per cent chromic acid, S parts 40 per cent formalin, 1 i)art glacial 

 acetic. This mixture has to be used as soon as it is mixed. 



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