December 17, 1915] 



SCIENCE 



873 



Land^ has recently described a fixing fluid 

 for paraiEn sections which is much superior to 

 the albumen fixative in general use. I have 

 been using a similar fluid for some time and 

 have found that it works equally well for cel- 

 loidin sections, and much better than the albu- 

 men method of fixation as described by Plow- 

 man. Land gives a formula for making the 

 fluid for paraffin sections, but for celloidin 

 sections I have found that by placing a few 

 small pieces of gum arable in distilled water 

 and shaking until the bubbles formed cease to 

 break readily, enough of the gum will be dis- 

 solved to answer all purposes. A sufficient 

 amount of potassium bichromate should be added 

 to give the fluid a slightly yellow color. Land 

 advises adding the bicromate when the sec- 

 tions are mounted, but by preserving the fluid 

 in a blackened bottle it will keep in good con- 

 dition for months. 



Two methods may be used in mounting the 

 sections. If they are small and the entire series 

 can be arranged on one or two slides, the knife 

 can be wet with 90 per cent, alcohol when 

 cutting, and the sections removed to a clean 

 glide as they are cut. After the slide has been 

 covered with sections, the alcohol is allowed to 

 dry, or is removed with a small piece of filter 

 paper. A drop of the fixing fluid is now added 

 and the slide tilted to allow it to run under- 

 neath the sections. The excess of fixing fluid 

 should be removed by placing a piece of filter 

 paper on top of the sections and gently press- 

 ing down. If care is exercised in doing this 

 it is very seldom that any of the sections will 

 adhere to the paper. Occasional sections that 

 do adhere, however, can be easily removed from 

 the paper and put in place again. Another 

 slide should be slightly oiled and placed on top 

 of the sections, after which it is clamped down. 

 The slide should be left to dry in strong sun- 

 light for a few hours. 



If the sections are rather large and it is not 

 necessary to save the entire series, the knife 

 can be wet with glycerine alcohol and the sec- 

 tions removed to a large slide or piece of glass 

 as they are cut. Such sections as are needed 



2Bot. Gas., 59, pp. 397-401. 



for study can be subsequently transferred to 

 another slide, first carefully washing them to 

 remove all traces of glycerine. 



If care is taken in removing the excess of 

 fixing fluid from the sections at the start, the 

 oiled slide can be removed after drying with- 

 out injuring any of them. I have mounted as 

 many as one hundred rather large sections in 

 series by this method and they all came through 

 in perfect condition. Alban Stewart 



University of Wisconsin 



the role of anopheles punctipennis say in 

 the transmission op malaria 



As the result of recent experiments con- 

 ducted in New Orleans, Louisiana, Anopheles 

 punctipennis Say has proved itself to be an 

 efficient medium for the development of the 

 sexual cycle of the organism of tertian malaria, 

 Plasmodium vivax. 



Of previous attempts to determine the exact 

 status of this species of Anopheles the most 

 thorough was that of Hirschberg who in a 

 series of carefully executed experiments ob- 

 tained only negative results in infecting A. 

 punctipennis with the gametes of estivo- 

 autumnal malaria. As further evidence of this 

 negative role, he states that no cases of malaria 

 were found to be developing in a certain sec- 

 tion of Maryland where the species was com- 

 mon, and that he had never found naturally 

 infected punctipennis here or elsewhere as had 

 been done with A. quadrim,aculatus. 



Dupree, however, in a list of efficient hosts 

 of malaria includes punctipennis as having 

 been so determined by himself. No other de- 

 tails are given and Knab in 1913 was inclined 

 to the belief that he had in reality experi- 

 mented with A. punctipennis, which is now 

 recognized as a distinct species and as an 

 efficient host. 



Anopheles punctipennis is one of the com- 

 mon species of the genus in the Uuited States 

 and because of its abundance and wide distri- 

 bution the question of its agency in the spread 

 of malaria is an important one. To record 

 the fact that the parasites of one form of the 

 disease may successfully develop in this species 

 is the purpose of the present note, which will 



