26 THE INITIATION OF DEVELOPMENT: 



the normal course of fertilisation, first a gelation of the proto- 

 plasm, the sperm aster, takes place, with the penetrating sperm 

 as its starting point. This spreads as an "onde de gelification" 

 in all directions through the egg cytoplasm. At the same time 

 the centre of the sperm aster solates (liquefies) again, and it 

 is only then that the amphiaster forms in this central area, 

 and that the nuclear membranes of the pronuclei, which have 

 in the meantime fused, disappear. In Bataillon's opinion, the 

 passing of this "onde de gelification" prepares the egg cyto- 

 plasm for the formation of an amphiaster, and thereby abolish- 

 es the anachronism between nucleus and protoplasm. In arti- 

 ficial parthenogenesis in Amphibia, the "onde de gelification" 

 starts from the cell fragments with which the egg has been 

 inoculated when it was punctured. Chambers (1921) has shown 

 that in Loeb's method the treatment of the sea urchin eggs 

 with hypertonic sea water causes an "onde de gelification" in 

 the cytoplasm around the nucleus. Therefore, Bataillon's hypo- 

 thesis, in contrast with that of Dalcq, is able to explain both 

 the phenomena of normal fertilisation, and those of artificial 

 parthenogenesis. In future, it may become possible to unite 

 both points of view into a single more general hypothesis, for 

 it must be admitted that in many cases the gelation of the 

 cytoplasm starts from the sperm nucleus. 



