Echinoderm Hybridization. 



147 



To facilitate comparison I combine all the statistics together m 

 Table VII. 



Table VII. — Comparison of results of cross-fertilization. 



Year. 



Cross. 



1909 

 1909 

 1909 

 1909 



1909 

 (i) 1910 



(2) 1910 



(3) 1910 



(4) 1910 

 (s) 1910 



1909 

 (i) 1910 



(2) 1910 



(3) 1910 



(4) 1910 



(s) 1910 

 1909 



Hip, c?' 

 Tox. ? 



Tox. (f 

 Hip. 9 



Hi p. 6" 

 Tox. ? 



Tox. c? 



Medium. 



Hip. 9 

 Hip. c? 



Plutei 



with 

 lattice 

 struc- 

 ture. 



sea-water 



sea-water 



sea-water-l- 

 NaOH 



sea-water-f- 

 NaOH 



sea-water-l- 

 acetic 



Tox. 9 



Hip. d' sea-water-t- 

 Tox. 9 ' ^^^^'^'^ 



Hip. 6" 



Tox. 9 

 Hip. 6" 



Tox. 9 



Hip. 6 " 



Tox. 9 



Hip. 6" 



Tox. 9 

 Hip. c? 



37 

 39 



Anal 

 arm 

 rods 

 with 

 lattice 

 struc- 

 ture. 



Hip. 9 



sea-water4- 

 acetic 



sea-water-l- 

 acetic 



sea-water-l- 

 acetic 



sea-water-t- 

 acetic 



sea-water-l- 

 HCl 



sea-water-t- 

 HCl 



sea-water-|- 

 HCl 



sea-water-l- 

 HCl 



sea-water-t- 

 HCl 



sea-water-l- 

 HCl 



sea-water-(- 

 acetic 



60 



S8 

 S7 



62 



7 



S 



16 



IS 



S 



6 



Arms 

 more 

 than 

 one 

 rod. 



Perfect 

 Hip- 

 pono'e 

 rods. 



Perfect 1 Perfect \ Perfect 



Toxop- Toxop- Hip- 



neustes ■ neustes ' pono'e 



rods. I plutei. ' plutei. 



38 



69 



30 

 15 



16 



Basket. 



The first results of 1910 did not tend to confirm those of 1909. As 

 I have already stated, another indication of Hipponoii dommance made 

 its appearance, this being the basket. This character seemed especially 

 difficult to control. The use of a greater amount of acid brought the 

 results of the previous summer. One interesting thmg m the work of 

 1910 was that the Toxopneustes ? X Hipponoe o^ hybrids lived better m 

 sea-water of reduced alkaUnity than in the normal sea-water. 



