Hermaphroditism among the Apodidce. 299 



epitlielium appears to have been dissolved into minute clear 

 round or oval cells each with a single ciiromosome. The 

 cells are from 4 to 5 /^ in diameter. In addition to these 

 cells there is a great quantity of slime. Near the basal 

 membrane these sperm-cells appear as if embedded in slime 

 (fig. 2 a), while the lumen of the tube is tilled up with a fine 

 reticulum of hardened slime, the meshes of which appear as if 

 they were round loculi from each of which one of the sperm- 

 cells has escaped. A few normal epithelial cells are seen 

 standing up among the sperm-cells ; 1 cannot make out that 

 any of them are in the act of breaking down. In all cases 

 the masses of sperm-cells abut directly against apparently 

 normal epithelial cells. 



Lepidurus glacialis. 



I have only one series of sections (longitudinal) through a 

 specimen from Greenland about 23 millim. long. Fio-. 3 is 

 drawn from a section passing through one of the genital tubes. 

 The membrane (w) above mentioned is seen dorsally held up 

 by the dorso-ventral muscles [dv] and ventrally under the 

 genital tube. The figure shows the section as seen under 

 a low power. The genital epithelium up to about the twenty- 

 fifth appendage (or twentieth leg) is completely disorganized, 

 but after this point apparently perfectly normal. The lumen 

 of the tube contains drops of slime, some large and clear 

 with a few black lumps in the centre, others small, all of them 

 highly refractive. The transition between the normal and 

 the disorganized epithelium is again quite sudden, but it is in 

 this case specially interesting. The disorganization seems to 

 be undermining the normal epithelium ; definite clear-cut 

 arches run under the epithelial cells, and these arched spaces 

 are filled with sperm-cells. 



Fig. 4 shows the ventral point of transition as seen under 

 the oil immersion lens. The cells again measure from 4 to 5 /i 

 in diameter. The distal ends of the epithelial cells seem to 

 be breaking down into slime. The free ends shown in the 

 figure are not necessarily detached, although appearing so in 

 the section. The arch running under these epithelial cells is 

 very clear, as it is also dorsally even with a low power (fio-. 3). 

 There is but one interpretation of this arching, viz. that which 

 is gathered from observations of the egg-formation. The 

 cell or cells near the basement membrane, on dividing to form 

 the four egg-cells, force apart the adjacent club-shaped epi- 

 thelial cells, which then arch over the developing elements on 

 all sides. We have in the figures now under discussion clear 



