BEHAVIOR OF CHROMATIN IN HYBRIDS 511 



4. The two types of chromosomes reappear in the spindle of 

 the second clea^'age, and can be distinguished throughout the 

 development, which was followed as far as the 12-hour stage. 



5. In the 12-hour stage large cells with irregular nuclei are 

 found, which represent the beginning of disturbances later shown 

 by abnormality or death of the larvae. 



6. There is no evidence of elimination of the paternal chroma- 

 tin at any stage. 



LITERATURE CITED 



Balt7er, F. 1910 I'eber die Beziehung zwischen dem Chromatin und der Ent- 



wickelung. Arch. f. Zellforsch., Bd. 5. 

 KuPKLAVEiSER, H. 1909 Entwickelungserreguiig bei Seeigeleiern durch Mol- 



luskensperma. Arch. f. Entw-Mech., Bd. 27. 



1912 Weitere Unters. iiber Entwickelungserreguiig durch stammf remde 



Spermien,. usw. Arch. f. Zellforsch , Bd. 7. 

 LoEB, J. 1912 Heredit}^ in heterogeneous hybrids. Jour. Morph., vol. 23. 

 MoENKHAUs, W. J. 1904 The chromatin in the development of hybrids. Am. 



Jour. Anat., vol. 3. 

 Tennent, D. H. 1908 The chromosomes in cross-fertilized Echinoid eggs. 



Biol. Bull., vol. 15. 



1912 a The behavior of the chromosomes in cross-fertilized Echinoid 



eggs. Jour. Morph., vol. 23. 



1912 b Studies in cytology. I and II. Jour. Exp. Zool., vol. 12. 



After the presen*^ article went to press a paper by Giuither and Paula Hertwig 

 on teleost hybrids appeared in the Archiv fiir Mikroscopische Anatomic (Bd. 84, 

 Heft 2), the results of which agree in general with the above conclusions, 

 though there is no case exactly parallel to that of Fundulus 9 X Ctenolabrus a". 

 The following points of agreement may be mentioned. The authors found no 

 case of elimination of chromatin, and in most cases the paternal and maternal 

 chromatin united, giving a perfectly normal cleavage. In all but one of the 

 heterogeneous crosses, the larvae died in the blastula stage, or whc^n the embryo 

 was just beginning to form, and at this time the only cytological abnormality 

 was the unusually large size of the nuclei. The case of Crenilabrus 9 X Box cf , 

 however, is different from their other heterogeneous crosses, for in this case the 

 larvae were very nearly normal. The}' were not, however, parthenogenetic lar- 

 vae, as can be shown from the size of nheir nuclei, and from the fact that they 

 inherit chromatophores such as are found in the male but not in the female 

 pan nt. With the general conclusion that the disturbance involves the relation 

 of nucleus and cytoplasm, rather than the nucleus alone, my results are in 

 complete accord. 



THE JOUHNWL OF E.XPEHIMENTAL ZOOLOGY, VOL. 16, NO. 4 



