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-lOthiuch. 



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. Rancid 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. Morjihology 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-lOth inch. Sew er 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; 1- 16th inch. Conidia. 



66. Ditto. Starch grain changing into C O2, 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 



