No. 526] SHORTER ARTICLES AND DISCUSSIONS 629 



be fertilized by tin* spermatozoa of the same individual. Morgan 

 analyzed tbe phenomenon in the light of immunity and was un- 

 able to demonstrate a parallel between the Cynthia immunity 

 and that in anti-body formation/' However, the ease described 

 by Morgan may not be equivalent to those of hybridization 

 experiments, such as we have described. 



Concerning the relation of the chromosomes to fertilization 

 and subsequent condition of the embryo, Bataillon 7 derives cer- 

 tain evidence from his amphibian crosses for the conclusion that 

 the number of chromosomes in the two parent species involved in 

 the cross is of importance in determining the condition of the 

 embryo resulting. Thus, when the number of chromosomes in 

 the two species is the same, no embryo results, while crosses 

 between species with different numbers of chromosomes lead to 

 progeny. If this observation is true, it might be due to the 

 fact that mainly, or only those chromosomes which are in excess 

 of the number occurring in the species with smaller number of 

 chromosomes and which do not pair up in synapsis with the 

 chromosomes of that species, are functional in producing the 

 embryo. Under these conditions, we should expect that the 

 embryo would resemble the species with the greater number of 

 chromosomes. However, this does not follow, inasmuch as 

 ISataillon did not observe nuclear copulation, but rather a mode 

 of artificial parthenogenesis is supposed to occur, the male ele- 

 ment being wholly without effect in inducing fertilization and, 

 therefore, the progeny would resemble the maternal species. 



In 1906, Emil Godlewski, Jr., succeeded in obtaining a few 

 hybrids between the sessile crinoid. Antcdon $ and Echinus ?, 

 thus involving two classes of echinoderms, the Echinoidea and 

 Crinoidea. The sperm exerted a marked inhibition of develop- 

 ment as a whole and the hybrids resembled the maternal Echi- 

 nus. This case is probably similar to the one described above 

 where non-compatibility is evident between egg and sperm nuclei 

 in fertilization. Godlewski did not examine the chromosomes 

 with a view to determining their condition in the cells of the 

 hybrids. 



