So THE MICROSCOPE. 



the blood. The value of the different kinds of illumination as to 

 central and oblique light with regard to observations of this charac- 

 ter was shown. While oblique light was really necessary to a satis- 

 factory definition of the striae of the diatoms, for the observation of 

 the blood corpuscle more central rays were required. The necessity 

 of using the test objects of the microscope, to be assured of the cor- 

 rect working of the lenses, before satisfactory work could be per- 

 formed, was commented upon. The powers used in these examina- 

 tions were from 600 to 2,400 diameters. The objectives used were 

 two of Spencer's 1-6 '"duplex" of 118" and 119° balsam angle and a 

 I- 16 inch objective of Gundlach. 



Mr. James W. Ward discussed the views presented. He did 

 not coincide with Dr. Heintzman, and stated that even were a 

 fibrillated structure to be found in the blood corpuscle, we would 

 be no nearer the end to be attained, viz., a knowledge of the struc- 

 ture of /;-<y/^^/^^i■w than before. A new fact would be simply added 

 to science. 



Dr. Barrett presented an interesting subject for consideration. 

 He exhibited a series of slides, prepared by Mr. Miller of Berlin, 

 in which the latter claimed that the dentinal tubuli were filled with 

 bacteria and micrococci — minute animal organisms which caused the 

 decay of the teeth. Dr. Fell and himself had examined the slides 

 and discovered the appearances set forth by Miller, but neither de- 

 sired to state positively that they were these organisms. The theory 

 heretofore held has been that the decay of teeth was of a chemical 

 nature. If micrococci and bacteria are founded in the dentinal tubuli 

 it would tend to upset this theory and undoubtedly be a great step 

 in advancing the causes of many abnormal conditions of not only 

 the teeth, but the human body at large. 



One of the slides which Dr. Barrett exhibited created a new 

 fact not, he thought, hitherto known to science. A slide made from 

 a sound human tooth showed that the enamel and dentine were both 

 penetrated by numbers of fungi of comparatively large size. Com- 

 mencing at the periphery these "spross pilz " had pierced the tooth 

 substance diagonally across the enamel rods and the dentinal tubules 

 to a considerable distance. It was not improbable that much of 

 what in tooth caries had heretofore been considered inexplicable, 

 might, in the light of Dr. Miller's observations, be readily accounted 

 for. 



