APPENDIX. 361 



judge from the description, are morphologically identical 

 with the monad in the blood of the carp. We have, how- 

 ever, seen that the organism in Surra is believed to be 

 pathogenic, and too much stress must not be laid on 

 morphological identity. There is strong evidence in 

 .favour of believing in its pathogenic properties ; but, at 

 the same time, it must be borne in mind that the organism 

 has never been isolated apart from the blood, and the 

 disease then produced by its introduction into healthy 

 animals. It is quite possible that the parasites in Surra 

 are only associated with the disease, the impoverished 

 blood affording a suitable nidus for their development, 

 while the contaminated water may be the common source 

 of the organism and of the disease. On the other hand, 

 the organism in the rat is found in apparently perfectly 

 healthy, well-nourished animals. 



APPENDIX C. 



EXAMINATION OF AIR. 



THE air, as is well known, contains in suspension mineral, 

 animal, and vegetable substances. The mineral world is 

 represented by such substances as silica, silicate of alu- 

 minium, carbonate and phosphate of calcium, which may 

 be raised from the soil by the wind, and particles of 

 carbon, etc., which gain access from accidental sources. 

 Belonging to the animal kingdom we find the debris of 

 perished creatures as well as sometimes living animals. 

 The vegetable world supplies micrococci, bacilli, and other 

 forms of the great family of bacteria, spores of other 

 fungi, pollen seeds, parts of flowers, and so forth. The 

 air of hospitals and sick rooms has been found to be 

 especially rich in vegetable forms, e.g., fungi and spores 

 have been observed as present in particularly large numbers 

 in cholera wards, spores of Tricophyton have been dis- 

 covered in the air of hospitals for diseases of the skin, and 

 achorion in wards with cases of favus. The tubercle-bacil- 



