262 MESSES. C. SHEAKER, W. DE MORGAN, AND H. M. FUCHS 



it with fresh water. This did not have any effect on his hybrids, they were only 

 rendered unhealthy. 



In a later series of papers, Hkrbst (39) gives the results of some experiments in 

 which he was able to change the character of inheritance through initiating 

 parthenogenesis in the eggs of Sphcerechmus, and then fertilizing them with sperm. 



He accomplislied this by treating the eggs for a short period wath valerianic acid 

 and then fertilizing them with Strongylocentrotus sperm. He got a displacement 

 of the type of inheritance in the maternal direction. His most important conclusion 

 was that the character of inheritance was influenced by the size of the $ and ^ 

 pronuclei at the time of their union. Incipient parthenogenesis gave an increase 

 in the size of the female pronucleus, and the resulting larvjB resembled the mother. 



In some instances he thought he obtained larvae maternal on one side of the body 

 while paternal on the other. He explained this by supposing that the spermatozoon 

 had entered the egg after the first segmentation division and thus was only able to 

 fuse with one of the daughter nuclei. 



GoDLEWSKi (30), in 1906, crossed JEchinus $ with Antedon $ &nd Strongylocentrotus 

 % with Antedon $ , and found a true fusion of the sperm and egg pronuclei taking 

 place. The chromosomes brought in by the Antedon sperm were incorporated with 

 those of the egg in the embryonic nuclei. The hybrids were maternal, developing 

 into Echinus-plutei. There was a high rate of mortality, and none of the larvse 

 survived more than a few days. Godlkwski concludes from these experiments 

 that in crosses between widely separated species such as Echinus and Antedon, the 

 sperm, although capable of initiating the developmental process and fertilizing the 

 egg, is unable to transmit its paternal characters. Godlewski also fertilized 

 enucleated fragments of Echiims eggs with Antedon sperm ; one of these fragments 

 developed as for as the gastrula stage and was of the maternal type. 



KuPELWiESER (48), in 1909, fertilized Echinus eggs with Mytilus sperm, and 

 decided that the sperm nucleus enters that of the egg, but does not fuse with it 

 nor give rise to chromosomes in the initial mitoses, but degenerates. 



In 1909, Hagedoorn (38), working at Loeb's laboratory at Pacific Grove, Cal., 

 crossed Strongylocentrotus puipuratus and Str. franciscanvs, and, from a study of 

 the apical ends of the skeletal rods, concluded that the hybrid larvse were purely 

 maternal. He also fertilized Strongylocentrotus eggs with Asterias sperm, and 

 again got larvse of the maternal type. In the following year, 1910, Loeb, King, 

 and MooRK (54) repeated this work and reached a totally different conclusion. 

 They state that each character is inherited separately, independently of whether 

 it comes from the paternal or the maternal side, and that one of a pair of such 

 allelomorphic characters is invariably dominant over tlie other. Tliey found the 

 clubbed form of skeletal apical rods to be dominant over the arched form, the 

 round shape of the larvae over the pyramidal, and the rough skeleton, early develop- 

 ment of the arms, and the development of the middle rod to prevail over the 



