and Laboratory Methods. 2291 



mens were transferred directly from absolute alcohol to a solution of dried 

 Canada balsam in absolute alcohol. The milky cloudiness produced in prepar- 

 ing this solution and also on placing objects in it disappears when the solution 

 or objects are kept at 60°C. for a few days. This method of mounting is 

 strongly recommended for Polyzoa, which are often badly disturbed by clove oil 

 in clearing. Densely calcified species were studied by removing the basal wall 

 with a scalpel from stained but not decalcified colonies embedded in paraffin. 

 The author is convinced of the great importance of studying the Cheilostomata 

 in undecalcified Canada balsam preparation. c. a. k. 



Argutinsky, P. Malariastudien. Zweite Mittei- The author states that the usual method 



June; : Zur Morphologic des Tertianpara- r i • i i i . • i ■ 



siten ^Plasmodunu rvrfrvGr. er Fel.). Arch. of drying blood preparations results in 



f. Mik. Anat. u. Entwick. 61: 33 1-34S, Taf. a distortion of the finer structure of 



^^"'' ^ ■ the malarial parasite. Alcohol and 



alcohol-ether are likewise poor fixers for nuclear structures. Fixation of dried 



blood films in aqueous or alcoholic sublimate affords fine elective staining, but the 



blood corpuscles and their parasites are still subject to the distortion caused by 



drying. On the other hand, the use of fluid fixers for undried blood is fraught 



with difficulty, on account of the great elasticity of the erythrocytes, and also 



because the fresh corpuscles are subject to swelling and shrinkage when 



placed in the anisotonic solutions used as fixers. Furthermore, the fluid usually 



washes away a considerable part of the blood smear even when greatest care is 



used. 



To obviate all these difficulties and at the same time secure perfect fixation 

 and fair stainability the author experimented with vapor methods. Formalin 

 fixes well, but interferes with the elective eosin-soda blue staining. Osmic acid 

 was finally selected as the most available fixing agent and was employed as 

 follows : From 6 to 10 drops of a mixture of osmic and acetic acids is placed 

 in a small low watch-glass in a Petri dish. The acids are thoroughly mixed 

 immediately before using in the proportion of 2cm.-^ of 4 percent, aqueous solu- 

 tion of osmic acid to one drop of 50 per cent, acetic acid. The slides with 

 blood smears prepared by the method of Janczo and Rosenberger are placed 

 smear down over the watch-glass as quickly as possible after preparation and 

 the Petri dish is closed. The slide is removed after an exposure of thirty 

 seconds, and is allowed to dry at room temperature for a few seconds only. By 

 this method 20 or more preparations may be made in a half hour. The slides 

 are bleached for 5 to 10 minutes in an officinal solution of hydrogen peroxide, 

 washed for 15 minutes in distilled water, dried between filters and then stained. 

 Since the osmium interferes somewhat with the staining it is necessary to use 

 well ripened and strong solutions of the soda-methylen-blue stain. The author 

 recommends 1 per cent, solutions ripened for three months in diffuse daylight. 

 After exposure to the stain for 30 minutes to an hour the preparations are differ- 

 entiated. Material thus prepared is most excellent for exhibiting the form and 

 nuclear structure of the parasite, even for the youngest stages, and is thus of 

 greatest clinical as well as morphological value. c. a. k. 



