64 J. p. HILL. 



they send lobose prolougations of their cytoplasmic bodies 

 inwards below the adjacent ectodermal cells, but they may 

 emit more or less elongated processes of indubitable pseudo- 

 podial chai'acter, which similarly lie in contact with the inner 

 surface of the wall-cells. Furthermore, Ave have evidence 

 that these pseudopodial processes may anastomose Avith each 

 other so as to initiate the foi-mation of an entodermal reticulum, 

 whilst the cells from which they arise are still constituents of 

 the unilaminar wall — an especially noteworthy phenomenon. 

 Certain of the primitive entodermal cells, as we have seen, 

 are at first devoid of such processes, but since they all 

 eventually form part of a continuous reticulum, it is evident 

 that the entodermal elements are capable of emitting pseudo- 

 podial processes as well after as before their separation from 

 the formative region. 



Finally, in view of the fact that the entodermal mother-cells 

 depicted in fig. 70 are not actually in process of division, and 

 therein differ from those of figs. 65 and 66, we may conclude 

 that the formation of the primitive entodermal cells is effected 

 either with or without the previous division of the mother-cells. 



If we admit, as I think on the evidence we must admit, 

 that the entodermal cells in Dasyurus are endowed with 

 amoeboid properties, then we are relieved of any further 

 difficulty in regard to the mechanism of their inward migration 

 from the unilaminar wall. Doubtless, in the case of those 

 entodermal mother-cells which do not undergo division, the 

 precocious formation of the above-described pseudopodial 

 processes which spread out from the cells like so many 

 suckers considerably facilitates their direct detachment from 

 amongst the cells of the wall. In the case of those primitive 

 entodermal cells which originate as the direct products of 

 division of the mother-cells, it no doubt depends on a variety 

 of circumstances (e.g. actual form of the dividing cell, 

 direction of the spindle, etc.) whether they exhibit amceboid 

 activity precociously (i.e. before their actual separation), or 

 only at a later period. 



The entoderm varies considerably in its degree of diffe- 



