Makch 26, 1915] 



SCIENCE 



475 



seasons show a lack of agreement with conditions 

 to be seen in most bradytictie or long period 

 breeders. The following counts illustrate this: 



GlocMdia of StropMtus edentuhis escaping at 

 various times during the spring from the parent 

 mussel were tested for reactions to sodium chlo- 

 ride, the blood of fishes and contact of fins. A 

 closing reaction was seen in each ease. This led to 

 an attempt at normal infection with entire success. 

 The juvenile stage was obtained after a parasitic 

 period of 27 days on the black bass. We have 

 failed, after studies covering two years, to ob- 

 serve development without parasitism in this spe- 

 cies. It would seem, therefore, that non-parasitic 

 development as reported for this species is excep- 

 tional. 



The Isolation of the OlcefinoTcee Sioamp Islands, a 

 Segregative or Convergent Factor in Species 

 Formation: Albert H. Wright. 

 The Beaotion of Herring and Other Salt-water 

 Fishes to Decomposition Products Normal to 

 Sea-water: V. E. Shelfoed. (With lantern.) 

 Herring are very sensitive to hydrogen sulfide 

 and carbon dioxide, dying very quickly in small 

 quantities of the former and more quickly than 

 fresh-water species in fatal concentrations of the 

 latter. They turn back upon encountering hy- 

 drogen sulfide in sea water and react to hydrogen 

 ions, selecting essential neutrality with a pre- 

 cision showing sensitiveness equal to litmus. 

 When differences in acidity are present they do not 

 react to differences in salinity and density. They 

 react to differences in temperature as small as 

 0.2° C. 



Some Sesults of the Indiana Lalce Survey: Will 

 Scott. 



Some Phenomena of Parasitism with Especial Ref- 

 erence to the Vnionidce: Arthur D. Howard. 

 The usual type of parasitism among the 

 Unionidffi is little more than commensalism, ap- 

 parently. The young mussel or glochidium is em- 

 bedded in the epidermis of the host, where in the 

 process of metamorphosis little besides protection 



and transportation are afforded. In addition to 

 this common and intermediate condition we meet 

 with two extremes; on the one hand, a pronounced 

 dependence upon the host in which considerable 

 growth of the parasite takes place as in the 

 Proptera group. On the other, a complete loss of 

 parasitism with independence of a host in which 

 the glochidium remains in the maternal marsupium 

 until the adult form is reached, as in Anodonta 

 imhecillis. The existence of these extremes with 

 intermediate gradations presents quite a range of 

 conditions. The observation of loss of parasitism 

 in Anodonta imbecillis brought up the question 

 as to how far the normal appearing glochidia had 

 lost the function for which their structure adapted 

 them. !Presh-eut fins with the blood from live 

 fishes were presented. The snapping reaction was 

 obtained. Infection on fishes was tried without 

 success until glochidia from a number of individ- 

 uals were used. Infection with complete encyst- 

 ment was then secured. They were not carried be- 

 yond this stage. 



The recognition of restricted parasitism among 

 the Unionidse has led to the discovery of some in- 

 teresting ecological relationships, such as Anodonta 

 pustulosa to the catfishes, Quadrula ehenus, to the 

 herring; Lampsilis anodontoides to the grapikes, 

 the Proptera group and the Plagiolas to the sheeps- 

 head. 



The relationship between Hemilastena ambigua 

 and Necturus is about the only ease of which we 

 have anything like a complete knowledge. The 

 others mentioned are only a few of those known 

 from hundreds of species of mussels the hosts of 

 which are not known. 



The elimination by fish of inappropriate mussel 

 parasites is a phenomenon which we have often 

 observed. The process seems to be one of catar- 

 rhal shedding of the external epithelial cells of 

 the fish's gills. Such mechanisms of immunity 

 raise the question as to the perhaps more wonder- 

 ful adaptations seen in the persistence of the para- 

 sitic glochidium when it finds the appropriate host 

 species. 



ProUems of Antarctic Bird Life: E. Gr. Murphy. 

 Some Experiments on Protective Coloration: B. G-. 



Young. 



The various theories of protective coloration are 

 based on the assumption of the usefulness of such 

 color. This has frequently been questioned, and 

 lacks as yet adequate experimental support. In 

 order to test the usefulness of color in protecting 



