140 THE AMERICAN MONTHLY [May, 



47. Pretubercular blood in a suspicious case, 1-lOth inch objective. 



48. Lard. A study, 1-lOth inch. Stearine crystals. 



49. Morphology of skin of 47. Cotton fiber, dirt in, 1-lOth inch. 



50. Morphology of air. Dust from top of office furniture, 1-1 0th inch. 



51. Morphology of skin of 47. A study, dermal epithelia and spores, 

 1-lOth inch. 



52. Morphology of air. Office furniture, near room top. Shows the power 

 of aerial flight residing in organic substances. A study. 



53. Morphology of food. Eancid butter. Shows butyric acid fermenta- 

 tion vegetation, mycelium. Study, 1-lOth inch. 



54. Morphology of blood. Pretubercular, 1-lOth inch. 



55. Morphology of blood. Mycelium of crypta syphilitica, l-16th inch. 

 56. Morphology of the blood of boils. A study. Quinia sulph. in a few 



days cleared the blood to normality, l-16th inch. Otherwise uninteresting. 



57. Morphology of air. Studies. Sewer gas, vegetations, conidia two. 

 Spores single, double, automobile, l-50th inch. 



58. Morphology of foods. Lactic acid fermentation from sour kraut, 

 1-lOth inch objective. 



59. Ditto. Yeast conidium active, with large vacuole. The large hazy 

 spots are automobile spores, l-50th inch. 



60. Ditto. Lactic acid vegetation, sour kraut, l-50th inch. 



61. Ditto. Gaff & Fleischman's yeast; larger conidia than common, l-50th 

 inch. 



62. Morphology of air. 1-1 0th inch. Sewer gas vegetations. 



63. Morphology of foods. Yeast, rye starch grain, yeast conidium, 

 bacteria and automobile spores, abundant, l-50th. 



64. Ditto. Yeast l-50th. Shows a fine bacillus probably tuberculous. 



65. Ditto. Yeast ; l-16th inch. Conidia. 



66. Ditto. Starch grain changing into CO2, glucose and alcohol ; l-50th 

 inch. Process that goes on in bread making. 



67. Ditto. l-50th inch. Butyric acid fermentation vegetation. My- 

 celial filament terminating with conidium. 



68. Microphotic apparatus of E. Cutter used with these original photos. 

 120 Broadway, August 1894. 



Diatom Growths in Surface Waters. 



By GEORGE C. WHIPPLE, 



BIOLOGIST OF THE BOSTON WATER WORKS. 



(Abstract of a paper published in The Technology Quarterly, Vol. VII, No. 

 3, October 1894.) 



For more than a century the study of the diatoms has 

 been a fascinating pastime. Much has been written on 

 the beauty of their form and markings, their animal or 



