THE FERTILISATION OF THE EGG 



25 



"regulation", such as is caused, e.g., by treatment of the sea 

 urchin egg with hypertonic sea water in Loeb's method. It is 

 true that in Bataillon's method for artificial parthenogenesis 

 in Amphibia regulation is caused by the introduction into the 

 egg of a blood corpuscle with its nucleus, but this nucleus does 

 not unite with the egg nucleus. Moreover, Einsele (1931) has 



Fig. 9. Two sections of a frog's egg, fertilised with two trypaflavin 

 treated sperms.-. : haploid nuclei, originating from the egg nucleus; 

 (f: sperm chromatin has remained compact; a: mitotic spindles with- 

 out chromosomes. After Dalcq. 



shown that the same result may be obtained with an extract 

 of blood or sperm. According to a recent investigation by 

 Shaver (1949), the activity of such extracts is mainly due to a 

 fraction consisting of cytoplasmic granules, so-called micro- 

 somes, which are very rich in ribonucleic acids. 



For these reasons, Bataillon has attempted an entirely differ- 

 ent explanation of the origin of dicentry. In his opinion, the 

 occurrence of a monastral cycle in activated eggs is due to an 

 "anachronism" between the development of the nucleus and 

 that of the asters arising from the cytoplasm. It is as though 

 the nucleus has proceeded further in its development than has 

 the cytoplasm so that the nuclear membrane disappears before 

 the aster has yet had time to develop into an amphiaster. In 

 normal fertilisation, the penetrating sperm accelerates the 

 activity of the cytoplasm. This "regulates" the phase difference 

 between nucleus and cytoplasm. Bataillon points out that, in 



