29? PROCEEDINGS OF THE ACADEMY OF [^^aj, 



tioned on mge 21)1). It will appear evident from figs. 4, A and 

 B, that six rows of cells, counting by the nuclei, are involved in 

 the typhlosole. 



(8) Syncytium. 



The very large cells which compose the adult " mid-gut" were 

 recognized by Huet to be without distinct parietal walls, but to be 

 bounded by rows of fibres. Ide figures cell walls for Onisciis 

 murarius, and thinks Huet was in error or overlooked them. 

 Almost simultaneously Mc^Eurrich and Schonichen put forward the 

 view that the epithelium is in reality a syncytium, the walls being 

 replaced by fibres which run from the intima to the basement 

 membrane. Both authors show that what Ide saw is undoubtedly 

 the chitinous lining, dipping in between the anterior cells on the 

 luminal side and the basement membrane, Avhich has a similar 

 relation to the coelomic side of the median cells. The syncytial 

 nature they argue further from the facts that the cells cannot be 

 separated by maceration in potash (a thing which Ide claims to 

 have accomplished) ; that neither silver niti-ate nor other stains 

 differentiate cell walls ; and finally, that the nuclei may be squeezed 

 through from one cell into another. Eyder and Peuuiugton (15), 

 who described these movements of nuclei as a natural phenomenon 

 (see page 304), figure cell walls, but do not state what becomes 

 of them when the nuclei pass through. Conklin, in showing that 

 the changes of position on the part of the nuclei are due en- 

 tirely to rough treatment, says : ' ' The parietal walls are so thin 

 that they cannot be distinguished." jNIy own observations confirm 

 those of the later writers. In the majority of cases of adult intes- 

 tines w'here I have looked for them, no sign of a wall is to be seen. 

 Figs. 15 and 16 represent the cytoplasm as perfectly continuous 

 from one cell to another. 



We have already spoken of the grooves which separate the ante- 

 rior cells on the luminal side. On account of these grooves the inter- 

 cellular fibres are shorter than the cell axes. The same is true for 

 the cells of the median portion and for those of the transitional re- 

 gion, but for a slightly different reason, While the intima does not 

 dip in between the median cells, the latter project into the ccelome 

 at their centres more than at the edges (fig. 12). The cells in the 

 transition region immediately posterior to the typhlosole show an 

 intermediate condition ; the intima does not dip in so deeply between 



