THE ROLE OF THE CELL ORGANS IN HEREDITY 



325 



plants, Guignard, Nawaschin (1910), and Welsford (1914) pointing out 

 that in Lilium only the male nucleus enters the egg, its accompanying 

 cytoplasm being rubbed off and left behind. (See p. 299.) Certain 

 ingenious experiments of Boveri (1889, 1895; also 1909 and 1918) led 

 to the same conclusion regarding the nucleus. Boveri induced the fer- 

 tilization of enucleated fragments of Sphcerechinus eggs (a phenomenon 



FIG. 127. 



A, egg of Sphcerechinus granularis undergoing artificially induced cleavage mitosis; 

 spermatozoon of Strongylocentrotus lividus has entered and taken the form of a chromosome 

 group. B, cytokinesis beginning; one blastomere will have a purely maternal nucleus, 

 and the other a hybrid nucleus. (Diagrammed after Hcrbst, 1909.) 



FIG. 127 bis. Diagram showing the irregular distribution of the chromosomes by a 

 quadripolar mitotic figure. (After Boveri.) 



known as merogony) by spermatozoa of Echinus, and obtained larvae 

 which were purely paternal in character. From this it was argued that 

 it is the sperm nucleus alone, and not the egg cytoplasm, that transmits 

 the hereditary characters from one generation to the next in this case. 

 Other experiments of a similar nature, however, turned out differently, 

 as will presently be noted. Certain echinoderm hybrids, furthermore, 

 show paternal larval characters even when the egg nucleus has not been 

 removed. 



