ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 327 



Joly's Method of Microscopic Measurement.* — J. Joly sag^rests 

 the following method of making microscojiic measurements by means 

 of the camera-lucida. Two line lines (fig. 48) are drawn with a 

 drawing-pen in indian ink on a piece of white paper. The camera- 

 lucida is placed in position, and the image of the object under the 

 Microscope referred in the usual manner to the sheet of white paper, 

 which is then shifted till the object appears to fit exactly between the 

 lines. While the object is still in view, a mark is made with a pencil 

 across the lines just where the object is referred. An engraved scale, 

 divided to 0"01 mm., is now substituted for the object, and a few, say y?, 

 of the subdivisions brought by the camera-lucida to fit, as before, be- 



FiG. 48. 



tween the lines. This point is also marked on the paper. The distances 

 d^ do of the two marks from the intersection point of the two lines are 

 then measured, and the diameter j' of the object is found from the pro- 

 portion X :n : : d^ : d.>. 



{6) Miscellaneous. 



Quekett Microscopical Club. — The 489th Ordinary Meetins: was 

 held on April 22. Mr. E. J. Spitta, F.R.A.S., T ice-President, in the 

 Chair. 



Mr. C. D. Soar, F.R.M.S., described two new species of water-mites. 

 These were Arrhenurus scourfieldi sp. n., from Cornwall, and Acercus 

 longitarsus sp. n., from South Devon. 



Mr. Ct. T. Harris, " The Collection and Preservation of the Hydroida." 



B, Technique. t 

 (1) Collecting- Objects, including- Culture Processes. 



Direct Cultivation of Tubercle Bacilli.}: — K. K. Wedensky de- 

 scribes a method by which tubercle bacilli may be cultivated directly 

 from animal tissues. The apparatus required consists of a number of 

 Erlenmeyer flasks containing 5 p.c. glycerin-broth, short silk threads 

 fastened at one end to small clamps, and sterilized dissecting instruments. 

 The threads are placed in test-tubes and sterilized in dry air. The 

 tuberculous material is removed under the most rigid aseptic or anti- 

 septic conditions, fastened into a sterilized clamp, threaded as above, and 

 suspended in a glycerin-broth flask in such a way that about half the 

 tissue projects above the surface of the liquid. The pieces of tissue so 



* Sci. Proc. Roy. Dublin Soc, xiii. (1913) pp. 441-2 (1 fig.). 



+ This subdivision contains (1) Collecting Objects, including Culture Pro- 

 cesses ; (2) Preparing Objects ; (3) Cutting, including Embedding and Microtomes ; 

 (4) Staining and Injecting ; ,(5) Mounting, including slides, preservation fluids, etc. ; 

 (6) Miscellaneous. 



; Centralbl. Bakt., Ite Abt. Orig., Ixviii. (1913) pp. 429-31. 



Z 2 



