No. 516] THE CUTICULA OF CESTODES 



719 



them in Distomum sp. (Fig. 12), Monticelli (1892, 1894) 

 in a number of trematodes, Nickerson (1902) in Cotylo- 

 gaster, Cerfontaine (1899) in Squalonckocotyle vulgaris 

 (Fig. 9) : many other authors also have seen and de- 

 scribed them. There can be no doubt that however one 

 may interpret the alleged "cuticularization of the embry- 

 onic and larval ectoderms,— and Brandes, Looss, Braun 

 and others will not admit that it has been demonstrated, 



— nuclei or nuclei-like bodies occasionally appear in the 

 cuticula of both larval and adult trematodes and cestodes. 

 These have been variously interpreted by different au- 

 thors. Blochmann (1896), for instance, asserts that they 

 are the end organs of sense cells which are imbedded in 

 the cuticula, while Looss (1893) thinks they may be por- 

 tions of formed material in the act of passing from the 

 parenchyma into the cuticula. 



It seems to me that the occurrence of nuclei in the 

 cuticula has been recorded by too many competent ob- 

 servers to be explained away in any such manner. They 

 undoubtedly do occasionally occur, being either nuclei 

 which are parts of a degenerating epithelium or perhaps 

 those which belong to the peripheral portion of the paren- 

 chyma and have become enclosed in the rapidly forming 

 and growing cuticula. This last probability is strength- 

 ened by the observation of Maelaren (1905) and others 

 that such nuclei occur most frequently in the cuticula of 

 young worms, and by those of Young (1908) and Cer- 

 fontaine (1899) who show, respectively, that the cuticula 



