ASCARIS CANIS (WERNER) AND ASCARIS FELIS 



(GOZE). 



A TAXONOMIC AND A CYTOLOGICAL COMPARISON. 



ARTHUR C. WALTON. 



(From the Zoological Laboratory of Northwestern University.) 



INTRODUCTION. 



Even to-day systematic helminthologists are not of one opinion 

 concerning the taxonomic relation of the Ascaris found in the 

 dog to the Ascaris found in the cat. Thus Glaue ('08, '09), 

 after a careful study of hundreds of individuals, maintains that 

 they are two distinct and separate species; whereas two other 

 workers, Schoppler and Kriiger ('12), declare quite as emphati- 

 cally that the differences between these two forms are not 

 specific differences, but differences in degree of development 

 only, and believe that these forms are merely varieties of Ascaris 

 mystax (Zeder). In 1911 Edwards made a cytological study of 

 Ascaris felis. The chromosomes in number and form differed 

 greatly from those described by Marcus ('06) for Ascaris canis. 

 Therefore upon a cytological basis, Edwards declared A. canis 

 and A. felis to be distinct species. Dr. S. I. Kornhauser, while 

 examining the germ cells of the Ascaris from the dog in con- 

 nection with the formation of di-tetrads, was struck by the 

 dissimilarity between his material and that studied by Marcus. 

 On communicating with Dr. Marcus, it was found that he had 

 obtained his material from a great variety of mammals which 

 died at the Munich Zoological Gardens. At the suggestion of 

 Dr. Kornhauser, the writer has made a careful taxonomic and 

 cytological comparison of A. canis and A. felis. Taxonomically 

 he is able to substantiate the work of Glaue; and cytologically, 

 that of Edwards; and to prove that Marcus was not dealing 

 with A . canis (Werner) . 



I here wish to express my thanks to Dr. Kornhauser for his 

 criticism of my work and the preparation of this paper, and to 

 Dr. Chas. Zell, of Chicago, for aid in obtaining material. 



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