ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 257 



floats thein on a beaker tilled with water, and then incubates them at 

 35°. After 3 or 4 days a culture of amoeba? and bacteria is fouud on 

 surface. After a few more days the amoebae are found in the encysted 

 stage. To obtain anguillulae the droppings of guinea-pigs or a mixture 

 of the droppings of guinea-pigs and rabbits are floated on the surface of 

 water in a vessel so as to make a continuous layer. After an incubation 

 at 85° of from 8 to 10 days, if the surface of the crust be scraped and 

 examined under- the Microscope, anguillulae will be easily detected. 



Differential Reaction for Bacillus coli communis and Bacillus 

 typhosus.* — Lippens finds that Bacillus coli exerts a biochemical action 

 on blood, and uses this to distinguish this bacterium from B. typhosus ; 

 2 c.cm. of physiological salt solution are placed in two test tubes and 

 then two drops of centrifuged and washed red corpuscles of the horse. 

 To the one tube is added 1 c.cm. of a young broth culture (24 to 48 

 hours) of the typhoid bacillus, and to the other a culture of B. coli. 

 The mixtures are shaken and placed in a rack. In 5 or 6 minutes the 

 reaction begins to show itself at the bottom of the coli tube, where the 

 mixture assumes a vinous violet hue. The reaction reaches its maximum 

 in 10 to 15 minutes, after which it fades away. The typhoid tube 

 remains unaltered. After having been placed in the rack the tubes 

 must not be handled or shaken. The paratyphoid and paracoli bacilli 

 give intermediate results. 



(2) Preparing 1 Objects. 



Studying the Development of Cecidomyidse.t — W. Kahle found 

 that fixing the larvae whole was useless. He therefore ripped up the 

 mother-larvae from head to tail with a needle ; this was done under a 

 dissecting Microscope, the insect being placed in salt solution. The 

 eggs or embryos were then transferred by. means of a capillary pipette 

 to the following fixatives : either formol-alcohol-acetic acid (30 parts 

 water, 15 parts 96 p.c. alcohol, 6 parts formol, and 1 part acetic acid), 

 or Flemming's fluid. The former was allowed to act for 5 hours, the 

 latter for 24 hours or more. The fixative is placed in a small tube, the 

 mouth of which is covered with gauze. After fixation is ended, the 

 fluid is removed by diffusion in upgraded alcohols. When dehydrated, 

 the preparations are transferred to a glass cube, with a concave floor, 

 by means of a camel-hair brush. In this is placed a mixture of alcohol 

 and oil of cloves. Oil of cloves is added drop by drop until the fluid in 

 the cube is approximately pure oil of cloves. The next step is to remove 

 the objects to a mixture of equal parts of oil of cloves and collodion 

 dissolved in ether, and thence to a glass plate, on which they are oriented 

 under a binocular dissecting Microscope. They are next treated with 

 xylol for 12 hours, and then, together with the glass plates, imbedded in 

 paraffin ; the plates are afterwards easily removed by immersion in 

 water. The sections were stained with carmin, anilin dyes, and haeina- 

 toxylin, of which Heidenhain's method proved the best. En masse 

 staining was best done with acid-carmin ; such preparations were either 

 mounted in resinous or aqueous media. 



The author, at the conclusion of his remarks on technique, mentions 



* C.R Soc. Biol. Paris, lxvi. (1909) pp. 95-6. 



t Zoologica, xxi. (1908) No. 55, 80 pp. (6 pis. and 38 figs.). 



