CHROMATIN — DEVELOPMENT AND HEREDITY 227 



egg fertilized with the sperm of Ctenolabrus gives purely maternal 

 larvae without eliminaticn of the foreign chromatin. 



Newman, too, believes that larvae which are phenotypically 

 pure maternal, still bear in their germ plasms the "full comple- 

 ment of paternal inheritance factors." Referring to such cases 

 as the above, he says, "We are therefore not dealing with a case 

 of parthenogenetic development, but with one involving a more 

 or less complete dominance of the egg over the sperm." This 

 and other of Newman's views may be more profitably discussed 

 later. 



Miss Morris' description of th^ Fundulus chromosomes agrees 

 with that of Moenkhaus, but, as I will show, she was in error 

 as regards the smaller chromosomes of Ctenolabrus. Ctenola- 

 brus chromosomes are rods, some of which have a length which is 

 several times that of their width. Many of the shorter elements 

 are hook-shaped, recalling one type of Echinoderm chromosome, 

 and a very few are so shcrt as to appear almost round, but their 

 width does not exceed that of the longer rods. It is possible 

 that a pair of small V-shaped chromosomes are present. The 

 width of the rod-shaped elements is exceeded only when the rod 

 is bent on itself to form hooks or Vs. 



My observations on the straight fertilized Ctenolabrus egg, 

 made in the summer of 1914 in connection with another problem, 

 suggested to me the possibility that the Ctenolabrus chromo- 

 somes in Fundulus eggs observed by Miss Morris were abnormal 

 as evidenced by their change in shape, and that this perhaps 

 accounted fcr their ineffectiveness in this cross. In the hope of 

 adding to our knowledge concerning the role of the chromosomes 

 in this and other Teleost crosses, I began the investigations, the 

 results of which are given in this paper. 



I am indebted to Professor D. H. Tennent for directing my 

 attention to this field of work and it gives me much pleasure to 

 express here my deep appreciation of his many kindnesses through- 

 out the course of my investigations. For the privilege of work- 

 ing at the Marine Biological Laboratory my thanks are due both 

 to Professor Frank R. Lillie, the director of the laboratory, and 

 to Bryn Mawr College. I am especially grateful to Mr. G. M. 

 Gray for his valuable assistance in supplying me with material. 



