484 EXPERIMENT STATION EECOED. [Vol. 36 



tissues, where the mode of reproduction is by encystation and spore formation. 

 The result of rapid reproduction is great thickening of the cecal wall. In 

 favorable specimens many of the features of flagellate morphology can be 

 observed in the parasites located in these regions. The liver presents a corre- 

 sponding appearance of the infecting elements, though more modified by their 

 location. 



" Very rarely the pathological condition may be complicated in the liver by 

 an amebic infection (not Atnwha mcleafjridis) and in the ceca by both amebas 

 and coccidia (Eimcria avium). The picture may also be complicated by infec- 

 tions vs'ith Hemoproteus. 



" The nature of the infective process, together with extensive clinical experi- 

 ence, makes it clear that intestinal flagellatosis can not be regarded as an in- 

 fectious disease, and that Trichomonas as found in these infections can not be 

 looked uix)n as a pure parasite. A successful infection depends upon factors 

 present in the host, and is probably quite unrelated to 'virulence' on the part 

 of the infecting organism. In this sense the infection, commonly called ' black- 

 head ' of turkeys, can not be regarded as an infectious or communicable disease. 



" The parasitic flagellates here described are identical with some of the 

 bodies earlier regarded by the writer as stages in the development of the 

 coccidium, Eimeria. They are also identical with bodies described by Theobald 

 Smith under the name .4. vieleagridis, of whose existence, as an ameba, up to 

 the present time no conclusive evidence has been brought forward." 



ETJRAL ENGINEEKING. 



The people's interest in water-power resources, G. O. Smith {TJ. 8. Geol. 

 Survey, Water-Supply Paper 4OO-A (1916), pp. 8). — This is an address delivered 

 before the Second Pan-American Scientific Congress at Washington, December 

 28, 1915. 



Accuracy of stream-fl.ow data, N. C. Grover and J. C. Hoyt (t7. S. Geol. 

 Survey, Water-Supply Paper J/OO-D (1916), pp. 53-5'J). — It is pointed out in 

 this repcn-t that " notes on accuracy that accompany stream-flow records should 

 give, first, information by which the technical man may study the records and 

 judge their accuracy, and second, information by which both the general and the 

 technical user may judge tlie reliability of the records without making a study." 

 The conditions affecting the accuracy of records of daily discharge are discussed 

 as " permanence of the stage-discharge relation, precision with which the dis- 

 charge rating curve is defined, refinement of gage readings, frequency of gage 

 readings, [and] methods of applying the daily gage heights to the rating table 

 to obtain the daily discharge." 



The measurement of silt-laden streams, R. C. Pierce (U. S. Geol. Survey, 

 Watcr-Supply Paper IfOO-C (1916), pp. 39-51, figs. 2).— An account of the special 

 difiiculties encountered and the results obtained in measuring the flow of the 

 San Juan River are given. 



Surface water supply of the Pacific slope basins in California, 1913 (U. S. 

 Geol. Survey, Water-Supply Paper 381 (1916), pp. 51^, pis. 2, fig. 1).— This re- 

 port, prepared in cooperation with the State of California, presents the results 

 of measurements of flow made on streams in the Pacific slope drainage basins 

 in California during 1913. 



Surface v/aters of Massachusetts, C. H. Pierce and H. J. Dean (U. S. Geol. 

 Survey, Water-Supply Paper Jfl5 (1916), pp. Jf33, pis. 12, figs. 6).— This report 

 describes the general features and gives the results of measurements of flow 

 made on streams in the Housatonic, Connecticut, Taunton, Charles, and Merri- 



