462 



SCIENCE 



[N. S. Vol. LIII. No. 1376 



Hypothetical Inorganic Composition of fhe Solution 



Per Cent. 

 Grams per Liter of Total 



Na^SiO^ 0.1460 1.84 



CaCHCOs)^ 0.2913 3.68 



OaSO. 0.8780 11.08 



MgSO, 0.8855 11.18 



MgCL, 0.3023 3.81 



KCl 0.5875 7.42 



Naao 4.8330 60.99 



Total 7.9236 100.00 



The Terrace crater, and indeed all of the 

 craters of the Ice Spring Craters group, is un- 

 questionably post-Bonneville in origin. There 

 is no trace of wave work on the outer slopes 

 of the craters such as are so conspicuous on 

 Pavant Butte to the north, and neither lacus- 

 trine sediments nor evidences of subaqueous 

 erosion appear on the surface of the evidently 

 recent lava fields as they do on the Fumarole 

 Butte lava field to the northwest. 



The depth of the vent of the Terrace crater 

 is 260 feet below its general rim and 220 feet 

 below the sill of the last outflow. The prob- 

 lem of the original introduction of Gammerus 

 into the small pool of water occupying the 

 bottom of this crater is that of the transpor- 

 tation of small crustacean species or their 

 eggs in general. The point of physiological 

 interest is the occurrence of this species, 

 hitherto reported from non-saline waters, in 

 water of this concentration. 



Eoss Aiken Gortner, 

 Division of Agricultural Biochemistry, Uni- 

 versity of Minnesota, 



J. Arthur Harris, 

 Station for Experimental Evolution, Car- 

 negie Institution of Washington 



9 An average value based on NaCl contemts of 

 4.8790 gr. calculated from residual Na and 4.7870 

 calculated from residual 01. The difference of 

 0.092 gram per liter is within experimental error 

 when one remembers .that the aibove calculations are 

 purely empirical and also when one considers that 

 in some instances the actual analytical values, and 

 consequently accompanying experimental errors, 

 were multiplied by 50 to bring the calculation to a 

 liter basis. 



AN EYELESS DAPHNID, WITH REMARKS ON 



THE POSSIBLE ORIGIN OF EYELESS CAVE 



ANIMALS 



During the past nine years vast numbers of 

 Cladocera of several species have been reared 

 in the writer's laboratory. For one purpose 

 or another many thousands of these have been 

 examined with the microscope. About a year 

 ago was found the only marked aberration of 

 the eye structure which has been noted. This 

 was a Simocephalus without any trace of an 

 eye. 



Unfortunately this individual was dis- 

 covered among the small number just killed 

 for use in making some permanent slide 

 mounts. The killing of this individual was 

 unfortunate in that a Cladoceran when kiUed 

 becomes somewhat opaque while the live ani- 

 mal is so transparent that internal structures 

 can be clearly distinguished. Nor was the 

 differentiation so good in the completed 

 mount as in a live animal. It was clear how- 

 ever both in the freshly killed specimen and 

 in the mount that not only the eye pigment 

 but the entire eye structure was lacking. The 

 ocellus was present and normally pigmented. 

 Wliile it is not quite demonstrated in the 

 mounted specimen it is probable that the optic 

 ganglion is normally developed in the eyeless 

 individual. 



It is a source of keen regret to the writer 

 that this eyeless individual was not discovered 

 alive so that offspring could have been ob- 

 tained from it and light thrown on the na- 

 ture of the peculiarity, whether of genetic 

 consequence or merely an accident in develop- 

 ment. No eyeless individuals were found 

 among sibs and many offspring of sibs of 

 this eyeless individual. This fact however 

 does not convince one that eyelessness in this 

 case may not have been inheritable, since in 

 these prevailing parthenogenetic forms there 

 is no chromatic reduction in the maturation 

 of the egg and hence no segregation of char- 

 acters is expected. If the eyeless condition 

 of this individual were due to a mutation its 

 descendants should have been eyeless, but un- 



