158 SUMMARY OP CURRENT RB8BAR0HES RELATING TO 



agar solution can be filtered ; while gelatin runs through with the 

 rapidity of water, and the apparatus has the further advantage of 

 sterilizing the solution at the same time that it filters it. 



Distinguisliing Stains of Human Blood. — We observe that in a 

 recent criminal trial an analyst deposed that human blood-corpuscles 

 could be distinguished from those of some other animals. This opinion 

 was based on the size of the corpuscles. 



It has been established by irrefragable evidence, both here and in the 

 United States, that this view is an entire mistake, and it is to be hoped 

 that the person charged in the case referred to will not be convicted 

 and hanged before the error is corrected. 



Methods for ascertaining the Number of Atmospheric Germs.* — 

 M. P. Miquel, who has done much for the analysis of germ-laden air, 

 has given up the insoluble " filter " for a plug consisting of a soluble 

 material. This device was suggested twenty-five years ago by Pasteur, 

 and dried Glauber's salt or dried sea salt have been recommended for 

 the purpose. Indeed, any soluble substance, when dry and sterilized, 

 and which does not act antiseptically, is suitable for the purpose ; and in 

 solving the problem required, i. e. of ascertaining how many germs were 

 imprisoned in the plugs, it would appear that oscillations of temperature 

 between 0^ and 30° made little difierence to the plugs. 



For the development of germs the necessary conditions are threefold, 

 viz. a suitable medium, a temperature of about 30°, and sufficiently long 

 period of observation (30-40 days). From numerous experiments it 

 was found that peptonized meat broth was far superior to peptonized 

 gelatin as a nutrient medium, only about one-half the germs really 

 existing in the air being developed on gelatin plates. 



The author concludes by maintaining that the gelatin-plate method 

 is inapplicable to air analysis in all those cases where the air contains 

 more fungi than bacteria germs. 



Method for determining the true Shape of Microscopic Objects.f 

 — ^Dr. E. Berger uses the following method for determining the shape of 

 the posterior chamber of the eye : — 



The objects are imbedded in celloidin on threads placed vertically 

 and set at a distance of 1 mm. The sections are made serially and are 

 marked numerically. The outlines of each section and of the transverse 

 sections of the rows are then drawn with the camera in such a way that 

 the last overlap. Then, if the thickness of the sections be known, the 

 projections, to adopt the phraseology of architects, &c., of the object 

 examined can be ascertained. 



The enlargement is found by calculating the distances of the images 

 of two sections, next each other in a row, by means of their true distance, 

 1 mm. For each enlargement it is easy to construct a scale so that the 

 real size of the object can be read off. 



Besbet, C. E. — Vacation Notes upon some Botanical Laboratories. 



[Strassburg, Leipzig, and Berlin.] The Microscope, IX. (1889) pp. 5-7. 



Beown, F. W. — A Course in Animal Histology. V., VI., VII. 



2he Microscope, VIII. (1888) pp. 336-7, 375-7, IX. (1889) pp. 12-14. 



* Ann. Instit. Pasteur, 1888, p. 346, 



t Comptes Rendus Soc. Biol., v. (1888) pp. 215-6. 



