684 EXPERIMENT STATION RECORD. tVoL 36 



*' The evidence points to several possible theories rather widely divergent. 

 The disease may represent a kind of aberrant parasitism, the true host being 

 some other species. Or the parasite may undergo its normal development in the 

 contents of the ceca, and the invasion of the tissues may be abnormal. Or there 

 may be still other stages and an intermediate host. These views can only be 

 definitely proved or disproved with the aid of the experimental method. The 

 writer does not feel committed to any one of these hypotheses. The results 

 obtained on feeding in 1913 and on exposing young artificially reared turkeys to 

 young diseased turkeys in 1914 were not definite enough to prove that infection 

 is direct from diseased bird to healthy, and they will require repetition and 

 amplification. 



" In casting about for a satisfactory method for raising trustworthy birds for 

 experimental work the writer found that healthy turkeys could be reared from 

 infected flocks by using the incubator and brooder. This procedure has made it 

 fairly evident that blackhead is not transmitted in the egg, although more trials 

 are needed before we can be certain of this." 



Aberrant intestinal protozoan parasites in the turkey, T. Smith {Jour. 

 Expt. Med., 23 {1916), No. 3, pp. 293-300, pi. J).— "There are so many points 

 of difference between the blackhead parasite and the unknown parasite of the 

 mucous membrane as encountered in this single case, that any attempt to pre- 

 sent them would require an elaborate restatement of what is now published. 

 Assuming that they are different, we are confronted with the fact that, even 

 after the blackhead parasite shall have been eliminated, the outlook for raising 

 turkeys without some losses due to avian coccidia and perhaps other still un- 

 known protozoan parasites is not very encouraging. Fortunately the mortality 

 due to these aberrant parasites was low. In any case the specific sources of 

 coccidia and other parasites must be found and dealt with." 



Hasstilesia tricolor, a common parasite of rabbits in the United States, 

 M. C. Hall {Jour. Amer. Vet. Med. Assoc, 48 {1916), No. 4, pp. 453-456).— The 

 author erects the genus Hasstilesia for Distoma tricolor described from Syl- 

 vilagus mallurus {Leptus sylvaticus) and L. americanus by Stiles and Hassall 

 in 1894. This is a very common intestinal parasite of rabbits in Maryland, 

 Virginia, and the District of Columbia and is also recorded from New York and 

 Texas. 



RURAL ENGINEERING. 



Reports on irrigation for the year 1915, E. F. Dbake and F. H. Petebs 

 {Dept. Int. Canada Ann. Rpt. 1915, pt. 7, pp. 23). — This includes the reports 

 of the superintendent and the commissioner of irrigation of Canada. 



Venturi meter succeeds in irrigation {Engin. News, 75 {1916), No. 24, pp. 

 1122, 1123, figs. 3). — A description of the adaptation of this well-known device 

 to the measurement of irrigation water is given. 



Determination of the maximum storm- water flow, C. E. Grunsky {West. 

 Engm., 5 {1914), No. 6, pp. 254-256, fig. 1). — This is a description of a new 

 method of solving the problem of rate of maximum run-off, involving a discus- 

 sion of the elements affecting its determination, the derivation of the Grunsky 

 formula for maximum rain intensity, and tabulated data showing its application. 



C 



The formula is /= -?=, jn which /=intensity in inches per hour, t=time in 



minutes, and C=a. coefficient to be determined from rain records. 



Determination of maximum stream flow, C. E. Gkunsky {West. Engin., 7 

 {1916), pp. 217-219). — From the formula for storm-water flow applicable to 

 small areas, noted above, an expression for maximum stream flow is developed. 



