1 , 2 SUMMARY OF CURRENT RESEARCHES RELATING TO 



that the eggs of one female gradually increased in size with increasing 

 age of the mother. The Nebraska eggs developed in about two hours 

 less time, on the average, than did the English eggs, and the time of 

 development was much more uniform than that of the English eggs. 

 The rate of egg-production in the Nebraska line was lower than that in 

 the English line, being a little over twelve per day per female in summer 

 in the former line, fifteen per day in the latter. Inasmuch as the 

 Nebraska eggs were the larger, the volume of egg-substance produced in 

 a uiven line by a single female was approximately equal in the two lines. 



More than 50 p.c. of the eggs of the English Rotifers were laid at the 

 surface-film of the water during the summer ; less than 10 p.c. of the 

 Nebraska eggs were laid at the surface, the remainder being cemented at 

 the bottom of the dish. The reason for this difference in the location of 

 the eggs is not known ; it may be due to a difference in the demand 

 for oxygen. Brief experiments tend to show that the difference in place 

 of egg-laying is not due to a difference in permeability. Temperature 

 appears to modify the percentage of eggs laid at the surface. 



The foot-muscles of the Nebraska females responded more vigorously 

 to chemical stimuli than did those of the English females, so that when 

 the animals were killed in a fixing fluid the foot of the Nebraska females 

 was often retracted completely within the body, that of the English 

 females being much more extended. 



Reciprocal crosses were made, and the inheritance of the above- 

 mentioned characters was traced through six filial generations. The 

 inheritance of the rate of egg-production and of the uniformity of the 

 time of egg-development was too irregular to summarize. As to the 

 other characters, in F x the English characteristics were dominant ; 

 in F 2 there was no evidence of segregation, all the lines showing 

 the English characteristics ; in F 3 , with one exception, all the lines were 

 like the English line in each of the four characteristics, the one excep- 

 tion being a line laying eggs of intermediate size. In F 4 there was one 

 line (perhaps also a second) that was exceptional in showing eggs inter- 

 mediate in size, while all the other characters of this line, and all four 

 characters in the other lines, were like those of the English line. 



The experiments show much less segregation than was to be ex- 

 pected. The characters of the English line appear to hang together, 

 the transmission of one being the same, with a few exceptions, as that 

 of all the others. It may be that the genes for the four characters are 

 somehow associated. But the facts are peculiar. 



Echinodernia. 



Ciliation of Asterids.*— James E. Gemmill describes the ciliary 

 currents in four species of starfishes — Asterins rubens, Solaster papposus. 

 Porania pulvillus, and Astrojwcten irregularis. The arrangement is 

 constant for all individuals in each of the species, and, except as regards 

 .xternal surfaces, is practically the same in all the species. Everywhere 

 'he arrangement of the currents corresponds to physiological needs. 



* Proc. Zool. Soc, 1915, pp. 1-19 (3 pis.). 



