434 C. H. TURNER 



has reached the following conclusions: — " 1. The animals of a 

 community are in agreement in the reaction to certain inten- 

 sities of two or more factors. These reactions may be used to 

 designate them. Thus the rapids community may be designated 

 as litho-rheotactic, meaning that the animals are arranged with 

 reference to current and stones of considerable size. 2. Animals 

 living in the same or comparable situations within the community 

 habitat are in agreement and the animals of different situations 

 react differently to these additional factors. Similar differences 

 are the physiological basis of strata and consocies though the 

 smaller number of species make the latter not easily distin- 

 guishable here. 3. Single species found in any community occur 

 in other situations where they are governed chiefly by stimuli 

 towards which there is not agreement of reaction throughout 

 the community to which they primarily belong." 



Wolcott (104) discusses the ecology of the parasitic wasp 

 Tiphia inomata. 



See McDermott under mating instincts. 



DISEASE SPREADING ACTIVITIES 



The papers of Graham-Smith (27), Harms (30), Lloyd (49,50), 

 Ludlow (54), Riley (74) and Webster (95) will be of interest 

 to physicians. 



Zetek (106) has demonstrated that the typhoid fever spread- 

 ing fly visits houses 2,500 feet away from the feeding places 

 of its larvae. 



Three theories have been proposed to account for the spread 

 of pellagra: (1) the zeistic theory, based on the work of Ballardini, 

 which appeared in 1895, which claims that it is a poisoning 

 due to the excessive use of the products of corn; (2) Mizell's 

 theory, proposed in 1911, which holds that it is poisoning due 

 to the use of cotton-seed products; Sambon's theory, dating 

 from 1910, which holds that it is spread by the sand-fly. Sambon 

 bases his theory upon the following statements: (1) the endemic 

 action in Italy has remained the same since the disease first 

 appeared; (2) the season of recurrence coincides with and fluctu- 

 ates with the season of the appearance of the adult sand-fly: 

 (3) in the center of infection whole families are attacked sim- 

 ultaneously; (4) in non-pellagrous districts the disease never 



