INDUSTRIAL PROGRESS DURING THE YEAR 1874. evil 



tule according to its environments: it is by no means the 

 case, as stated by him, that those contained in gelatinous en- 

 velopes are less developed in strength of shell and bracing ; 

 for example, Encyonema jjrostratum is an exceedingly stout 

 form, and contained in remarkably stout tubes, while Fragi- 

 laria striatella, attached to algse in running brackish water, 

 is so feebly silicious that it will not stand acid treatment at 

 all. Closely connected with microscopic examination of 

 markings and structure of diatoms, we may notice the result 

 of Professor Abbe's researches, published in a late number of 

 Max Schultze's Archiv. He arrives at the conclusion that 

 the limit of capability is almost reached by our best micro- 

 scopes, and that all hope of a deeper penetration into the 

 material constitution of things than such microscopes now 

 afford must be dismissed, experiment and theory both show- 

 ing that the changes wrought by diffraction, in the examina- 

 tion of very minute structures, are such that different struct- 

 ures may give the same microscopical image, or like struct- 

 ures different images. 



Blood. The origin and development of the colored cor- 

 puscles is stated by Dr. D. H. Schmidt, of New Orleans, so 

 far as the human embryo is concerned, to be sought in the 

 gland-like follicles of the umbilical vesicle, differing of course 

 entirely, as he admits, from the older observations, as also 

 from the later, of Klein and those of Balfour. 



In a paper read before the Biological and Microscopical 

 Section of the American Academy of Sciences, Dr. Joseph J. 

 Richardson states that we are now able, by the aid of high 

 powers of the microscope, and under favorable circumstances, 

 to positively distinguish stains produced by human blood 

 from those caused by the blood of any of the ordinary do- 

 mestic animals ; and this even after a lapse of five years 

 from the date of their primary production. 



It is now pretty generally agreed that bacteria are almost 

 invariably present in the blood, but Dr. Eberth (in Central- 

 blatt, No. 20, 1873) has found them in ordinary perspira 

 tion ; in spots covered with hair they attach themselves 

 to the hair, often forming thick lavers. He thinks thev 

 are very likely to produce certain chemical modifications of 

 sweat. 



Careful microscopic examination has shown that caries in 



