DESCRIPTION OF El-HYPATIA BLEMEIKGIA. 107 



yolk-oodies {yo.body)., aho tlie columnar cells which are as yet oulv an aggre- 

 gation of amoeboid wandering cells with food vacuoles and yolk-bodies, also 

 the " trophophores " which possess clear protoplasm, but no yolk-bodies or 

 food vacuoles. 



Fig. 12 (x 130). — A representation of a stage slightly later than that 

 shown in Fig. 11. Note that the amoeboid wandering cells outside are 

 becoming columnar, especially on one side, also that the outer cells are 

 becoming separated, from those which are becoming columnar, lo form a kind 

 of loose membrane (of. Fig. 14). 



Fig. 12« (X 950). — A representation, more highly magnified, of the 

 amoeboid wandering cells, which are becoming columnar on one side of the 

 section shown in Fig. 12, and also, on the left side of the figure, of the cells 

 which begin to form the loose membrane, 



PLATE 3. 



Fig. 13 (x 130). — A representation of a stage slightly later than that 

 shown in Fig. 12. Note that the column;ir layer is complete except over a 

 small portion at which, later on, the pore will appear, and at which alone the 

 " trophocytes" {troph.) are found; also that the inner chitinous layer is 

 being formed from the same position, i. e. from the bottom, as the columnar 

 layer of cells was formed. 



Fig. 13« (x 1150). — A representation of a portion of a section similar to 

 the one shown in Fig. 13. Note the group of six trophocytes {tropho.) 

 which are making their way to the interior of the gemmule, also the " tropho- 

 cyte" which has already reached that position. This group is an unusually 

 large one, and was found opposite one of the strands of tissues which jjass 

 from the sponge tissue to the loose membrane which surrounds the gemmule. 

 The " trophocytes" ai>pear to travel chiefly along these strands of tissue. 



Fig. 136 (x 1150). — A representation of a similar portion to tliat shown 

 iu Fig. V6a. Note that the "trophocytes" {(roph.) are scattered about 

 among the amoeboid wandering cells, which later on become the colunniar 

 cells. On the left of the figure is seen the end of one of the strands of tissue 

 along which the trophocytes travel. Also note the trojihocyte on the right 

 of the figure. This cell is just passing among the yolk-cells {yo. cell). 



Fig. Vic (x 960j. — A representation of a portion from the top of a section 

 similar to the one shown iu Fig. 13. Note that the " trophocytes " {(roph.) 

 are arranged chiefly outside the columnar cells, but that there are some 

 situated still among the yolk-cells. Those outside have already travelled out 

 while those inside are in the process of doing so. In the lower part of the 

 section there were no "trophophores." 



Fig. Vdd (x 1150). — A representation of a yolk-cell from the same section 

 as Fig. 136', Note the large, central, vesicular nucleus (««.). 



