THE ROLE OF THE (ELL ORGANS IN HEREDITY 



325 



plants, Guignard, Nawaschin (1910), and Welsford (19] \ pointing out 

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

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

 ingenious experiments of Boveri (1889, L895j also L909 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 granulans undergoing artificially induced cleavage 1 1 1 i t « .- i ~ ; 



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

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

 ami the other ;i hybrid nucleus. (Diagrammed after Herbst, !!><)<».) 



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 thai 

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

 the hereditary characters from one generation to the next in tin's case. 

 Other experiments of a similar nature, however, tinned oul differently. 

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

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

 removed. 



