1911] Watson: The Genus Gyrocotyle. 395 



transverse and longitudinal muscles and of nucleus some distance 

 removed from the fibre in the subcuticular muscles, corresponds 

 to the classification given by Braun (1901, p. 1351). The only 

 difference is that the laterally attached nucleus in Gyrocotyle is 

 inside the fibre, not in an adjacent myoblast. The occurrence of 

 nuclei within muscle fibres is reported, according to Braun (1894, 

 p. 1351) in the scolex of the Tetrarhyncha, and in the longitudinal 

 muscles of the proglottides of Taenia dendritica. That a form 

 as primitive as Gyrocotyle should exhibit a muscle fibre relatively 

 simple and undifferentiated as compared with that of the mero- 

 zoic cestodes, is exactly what other facts in its structure would 

 lead one to expect. 



The staining reactions of the muscle-fibres are of some 

 interest. With iron hematoxylin and toluidin blue the whole 

 fibre stains very intensely. Preparations by these methods are 

 excellent morphologically, mapping out the muscles most sharply ; 

 but are quite worthless histologically. With Mallory 's connective 

 tissue stain, muscle fibres stain a bright red. As nuclei also stain 

 red, this method is not useful for a study of muscle-nuclei. The 

 same holds true for borax carmine-Lyon 's blue preparations. 

 The best results are given by Delafield's hematoxylin, hematoxy- 

 lin-eosin, or Mayer's acid haemalum, and counter-stains. With 

 these the muscle-fibre stains a dull blue-gray, while the nucleus 

 comes out sharply in blue-black. 



IV. REPRODUCTIVE ORGANS. 



The organs of Gyrocotyle include the following : 



1. Female. Ovaries, receptaculum ovorum, vitellaria, shell- 

 glands, uterus, vagina, and receptaculum seminis. 



2. Male. Testes, vasa efferentia, vesicula seminalis, vas 

 deferens, penis, and prostate glands. 



All of these organs, with the exception of the vitellaria, lie 

 within the inner longitudinal muscles. The female organs are in 

 the second and third quarters of the length of the body ; the male 

 organs in the first quarter. 



The ovaries (ovar., pi. 39, fig. 42) lie laterad of the uterus, 

 at its posterior border. They are roughly triangular in shape, 

 the lateral lobes united in the median line just posterior to the 



