February 14, 19] 3] 



SCIENCE 



263 



moiia endures such heat easily. The arrangement 

 of the scales on the two forms is likely a part of 

 the explanation of the distribution, since they lie 

 flatter and less loosely on Lepisma than they do 

 on Thermoiia. Further observations are being 

 carried on with reference to the moisture relations 

 of the two forms in these habitats. 

 V. E. Shelfobd (University of Chicago) : An 



Experimental Study of the Beactions of certain 



Animals to Gradients of Evaporating Power of 



Air. (Lantern.) 



Millipedes, ground beetles and amphibians in- 

 habiting moist forests react negatively, usually by 

 turning back, when they encounter air of high 

 evaporating power. The negative reaction usually 

 begins after several trials of the air of high 

 evaporating power. The reactions are similar 

 when the evaporating power is due to current and 

 when due to dryness, but in some cases they are 

 more pronounced when it is due to higher tem- 

 perature. Comparable animals from habitats 

 where evaporation is great do not react sharply 

 to the gradients used with the forest animals. 

 Sharpness of reaction is not correlated with the 

 length of time required to kill the animals with 

 dry air. 

 J. W. Scott (Kansas Agricultural College) : The 



Viaiility of certain Cystocerci in Pigs and in 



Young Dogs. 



A series of experiments was tried to determine 

 whether hogs are injured by feeding upon rabbits 

 that are infected with the cysticerci of T. serrata 

 and T. serialis. When corn is scarce it is a com- 

 mon practise for farmers in the western part of 

 Kansas to feed jackrabbits to their hogs instead 

 of corn. The intermediate host of T. serrata is 

 the cottontail or common wild rabbit, but this 

 parasite is occasionally found in the jackrabbit. 

 In the vicinity of Manhattan out of a total of 

 sixty-one rabbits examined during the winter of 

 1911-12, fifty-one (nearly 84 per cent.) were in- 

 fected with cysticerci of T. serrata. The multiple 

 cyst of T. serialis is found occasionally in the 

 cottontail but is very common in the jackrabbit. 

 This cyst may grow as large as a goose egg, and 

 a single jackrabbit may have as many as half a 

 dozen or more of these so-called ' ' waterblisters ' ' 

 in various stages of development. Cysticerci from 

 both species of tapeworms were fed to pigs weigh- 

 ing from seventy-five to ninety pounds, care being 

 taken to prevent injury to the cysts before they 

 were swallowed. Though a large number of cys- 

 ticerci were fed, not a single tapeworm was found 



when the pigs were killed ten days later. When 

 the same kinds of cysticerci were fed to young 

 dogs from 90 per cent, to 100 per cent, were 

 recovered in the form of young tapeworms. These 

 experiments indicate a very high degree of special- 

 ization of the parasite with reference to its opti- 

 mum environment. 



A full account of these experiments, together 

 with the time required for transformation, rate 

 of development and effect upon the definitive host, 

 will be published later. 

 C. C. Adams (University of Illinois) : Ecological 



Surveys. 



E. H. WOLCOTT (University of Nebraska): (1) 

 Some Aspects of Faunal Conditions in Western 

 Nebraska. (Lantern.) (2) Biological Work in 

 the Alkali LaJces of Cherry County, Neb. 



F. B. ISELT (Central College) (introduced by W. 

 C. Curtis) : Experimental Study of the Growth 

 and Migration of Fresh-water Mussels. 



About 900 specimens, representing eleven spe- 

 cies, of fresh-water mussels were tagged, weighed, 

 measured, initial records taken and planted (re- 

 turned to the stream or pond) by the writer in 

 June, 1910. Many of these specimens were re- 

 claimed, a number of times, and further records 

 taken in 1910, 1911, 1912. Tabular results con- 

 cerning the growth and migration of 122 of the 

 specimens under observation are given. 



A few points from the summary may be stated 

 as follows : 



1. Rate of growth is exceedingly variable. 



2. The summer months are the growth months. 



3. Lines of arrested growth may be called rest 

 rings, the conspicuous ones being usually winter 

 rest rings ; occasionally, the rest rings may be two 

 or more years apart, more often, however, several 

 equally prominent rings may be formed in one 

 year. Prominent rest rings are generally due to 

 double prismatic and epidermal layers. 



4. Under favorable environmental conditions- 

 there is little migration, especially among th& 

 Quadrulffi. 



J. E. WoDSEDALEK (introduced by A. S. Pearse) : 

 Some Results of Stiidies on Behavior and Star- 

 vation of Dermestidw. 



Nathan Fasten and George Wagner (Univer- 

 sity of Wisconsin) : The Behavior of a Parasitic- 

 Copepod, LerncBopoda edwardsii. 

 This copepod is exclusively parasitic on the 



brook trout (Salvelinus fontinalis). During its 



free-swimming existence, not more than two days- 



