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THE AMERICAN NATURALIST [Vol. XLIII 



the cuticula by means of ducts passing between the super- 

 ficial muscle fibers. Brandes's theory is based upon an 

 examination of a considerable number of monogenetic 

 and digenetic trematodes, in both of which groups he finds 

 practically identical structural conditions in the cuticular 



main difference between his theory and that of Blochmann 

 lies in their interpretation of the subcuticular cells, the 

 former holding them to constitute a hypodermis and to be 

 consequently an epithelium of ectodermic origin, the latter 

 considering them simple gland cells which are derivatives 

 of the parenchyma. 



These important theories, although they may seem to 

 account for the facts in the animals investigated and to 

 place the whole matter upon a substantial logical basis, 

 have, however, met with considerable opposition, and, it 

 seems to me, are not well grounded. It is quite evident 

 that if they are true they must have universal applica- 

 tion. If the subcuticular cells are the matrix of the cuti- 

 cula, whether we consider them to be single-celled glands 

 or the constituent parts of a hypodermis, then they must 

 be present in all trematodes and cestodes, since this pecul- 

 iar cuticula characterizes all of these worms (with the 



and subcuticular layers. His 

 drawings, however, are very 

 diagrammatic. The subcuticu- 

 lar cells certainly do not exist 

 in any trematodes in the form 



in which he shows them, and 

 those in his figures of mono- 

 genetic trematodes are not the 

 subcuticular cells at all, but the 

 single-celled glands which are 

 present at the forward end of 

 most of these worms. 



Tennent (1906) and others 

 have adopted Brandes's view. 

 It will at once be noted that the 



