504 "summary of cuerent researches relating to 



the mark 1, and diluting fluid drawn in until the whole stands at 101, 

 a mixture of 1 p.c. is obtained. A glass pebble in the cavity assists the 

 uniform intermixture on shaking. 



Numeration of Blood-platelets.* — G. Vallet advocates the following 

 method for the enumeration of blood-platelets. A drop of 1 p.c. osmic 

 acid solution is placed on the back of the thumb just above the nail, and 

 a needle-prick is made across the drop. Some of the mixture of blood 

 and osmic acid is drawn up into a fine pipette, and a very small drop is 

 transferred at once to a clean cover-slip. The specimen is then fixed for 

 half an hour in absolute alcohol, and stained with Giemsa's solution for 

 two hours, washed in water and dried. Fifteen to thirty fields are then 

 examined, and the hajmatoblasts and leucocytes are counted, and their 

 relative proportions noted. The exact number of leucocytes in 1 c.mm. 

 being known from a corpuscular count, it is easy to calculate the number 

 of platelets. 



Convenient Laboratory Devices.f — J. S. Fulton describes various 

 laboratory accessories : («) A dust-proof sterilising and storage box for 

 Petri dishes, consisting of a brass base with three upright arms, two of 

 which are fixed and one pivoted and bearing a loose riveted ring ; the 

 plates are stacked against the fixed arms, the loose arm is raised and the 

 ring slipped over embracing the two uprights ; a cylindrical cover is 

 then slipped down between the uprights and the plates, thus forming a 

 dust-proof package. 



(b) A cage for holding inoculated plates during incubation. It con- 

 sists of a brass plate carrying two bent wires that cross in contact at a 

 convenient height, forming four uprights against which the plates may 

 be stacked ; a similar wire loose- jointed to the base crosses the other 

 two, and engages a notch at the middle of the bend where all the wires 

 cross ; by pressing the two stiff wires together the space on the opposite 

 side opens enough to allow the plates to be stacked ; the loose arm is 

 then swung up and sprung into the notch, converting the whole into a 

 safe package. 



(c) A tray for fermentation tubes. This consists of a brass plate 

 carrying twelve brass pins IJ inch high, over which are slipped the 

 hollow stems of the tubes ; into the end of each pin is sawn a fine slit, 

 into which is fixed a piece of rubber band, which grips the side of the 

 glass stem and prevents wobbling. 



(d) An express package for samples of water for bacteriological 

 examination. 



(e) A portable charcoal oven for making plate cultures at the well side. 

 (/) An extensible box for carrying inoculated plates. 



{g) A scale for reading gas percentages in fermentation tubes. 



(h) A new form of water-bath, by which within 10 minutes as many 

 as 70 test-tubes of solid culture material can be melted and cooled 

 ready for inoculation. 



* C.R. Soc. Biol. Paris, Ixii. (1907) p. 540. 

 t Centralbl. Bakt., Ite Abt., xliv. (1907) p. 89. 



