No. I.] THE EGG OF UMAX AGRESTIS. 223 



sublimate acetic (5 per cent), and also in picro-acetic ; all these 

 agree in showing similar structures at corresponding periods. 



The archiamphiaster in the ^^^ of Limax is of particular 

 interest, as the centrosphere corresponds very closely to the 

 type of centrosphere in which Boveri first described the "archo- 

 plasm " in the eggs of Ascaris. In Limax the outer zone of the 

 centrosphere, which corresponds to the " archoplasmic " zone of 

 Boveri, appears as a deeply staining homogeneous ("cortical") 

 zone surrounding a clear ("medullary") zone which is not 

 stained by any of the methods used in coloring the prepara- 

 tions. The contrast between the " cortical " zone of the centro- 

 sphere, or the " archoplasm," and the cytoplasm is sharpest in 

 those eggs that have been killed and hardened in their cap- 

 sules in Flemming's solution. This shows that the appear- 

 ance of the "archoplasm " is sometimes modified by the killing 

 reagent. It is not, however, produced by it. 



When the sections are treated with the double stain, Lyons 

 blue and borax-carmine, the centrosome and "cortical" zone 

 ("archoplasm") of the centrosphere both stain blue, while the 

 spindle, the astral rays, and the cytoplasmic network take the 

 red stain of the carmine. After the first polar globule has 

 been extruded and the egg-centrosphere has become uniformly 

 granular in appearance, as shown by PI. XI, Fig. 14, the whole 

 centrosphere takes a faint bluish stain after Lyons blue and 

 borax-carmine. The second maturation spindle is formed within 

 the blue staining centrosphere, and if Boveri's theory of archo- 

 plasm holds, the second maturation spindle should stain blue. 

 This is not the case, however. The astral rays of the second 

 viaturation spindle are red like the cytoplasm, even while the 

 spindle lies within the centrosphere. The centrosomes of the 

 archiamphiaster appear faintly bluish, but even the tendency of 

 the centrosomes to take the blue stain constantly diminishes. 

 At this stage the Zwischenkorper of the first polar globule also 

 stains blue, like the archoplasmic zone in the archiamphiaster 

 stage. 



After the extrusion of the second polar globule the distinc- 

 tion between those structures in the astrosphaere that stained 

 blue and those that stained red in the earlier stage is still 



