No. 500] NOTES AND LITERATURE 



561 



assuming that some of both sexes get through successfully, then 

 meeting each other, as against the possibility of either meeting 

 and pairing with or being paired with a male or female of the 

 much more abundant parent form, is so remote that one puts 

 aside the possibility." 



The instances of mongrelization are classified under the fol- 

 lowing headings: 



1. Crossing of typical form and local race. 



2. Crossing of typical form and aberration; production of 

 artificial races by inbreeding. 



3. Crossing of typical forms with aberrations tending to de- 

 velop melanochroic races. 



4. Crossing of typical form with aberration trying to set up 

 local race. 



5. Crossing of dimorphic forms of a species which occur to- 

 gether and rarely appear to attempt to supplant each other. 



6. Crossing of typical forms with possible constitutional aber- 

 rations. 



7. Dimorphism in one sex. 



It is impossible to give any summary of the many cases de- 

 scribed under these headings, but enough has been said to show 

 how valuable the work is to students of evolution and variation. 



T. D. A. COCKERELL. 



PARASITOLOGY 

 Parasitic Diseases in the Philippines — The paramount impor- 

 tance of zooparasitie diseases in the Philippines may be judged 

 from the recently published record of the bureau of health since 

 the medical work at Bilibid Prison was placed under its charge 

 in November, 1905. The prevailing diseases treated in Hospital 

 A, Bilibid Prison, were hookworm, 1,537 cases; amebic dysen- 

 tery, 551 cases; acute dysentery, 174 cases; cholera, 18 cases; 

 pneumonia, 62 cases ; beriberi, 60 cases ; conjunctivitis, 221 cases, 

 and malaria, 174 eases; 81 per cent, were thus due to animal 

 parasites. The death rate decreased from 238 per thousand in 

 1905 to 13.5 per thousand in June, 1907. General sanitary 

 measures were responsible for the first reduction to about 75 per 

 thousand; active measures against animal parasites led to the 

 further reduction. 



