72 REVIEW — TROPICAL MEDICINE, ETC. 



Filariasis — 2. Removal of wings and legs in the same liquid, in a watch-glass. 



coiUinmd 3. Equal parts of absolute alcohol and ether, 24 hours. 



4. Weak solution of celloidin, 24 hours. 



6. Thick celloidin, 24 hours. 



6. Mounting on block. 



7. Chloroform, 20 minutes. 



8. Eighty per cent, alcohol until ready to cut. 



The sections were always stained in Bohmer's haematoxylin, followed in some cases by eosin and in others by 

 van Qieson's solution. 



Dissection — 



The living insect is placed in a test-tube with a small amount of water, and is shaken until the wings become 

 wet, and the insect floats on the water. The liquid is poured into a watch-glass, where the legs and wings are 

 pulled oflt by means of forceps. 



The further dissection should be made in the following order ; — 



Dissection of the abdomen upon a slide, constantly irrigating the mosquito with distilled water or weak salt 

 .'ioUition. After dissection place under microscope and determine by medium power whether there are any filariae. 

 The head and thorax are transferred to another slide. Here the chitiu is broken near the neck, and the head is 

 transferred to another slide. Each part is thus dissected separately, and we are able to determine the localisation 

 uf the parasites. If the latter be well advanced in their development, they push their way out through the 

 openings made in the chitinous covering at the time of dissection. 



If we wish to preserve the specimens, the filariae, if they are large enough, are transferred from place to place 

 upon the slide, and repeatedly washed, while we clean and remove all detritus of the body of the mosquito from 

 the slide. We finally add a drop of mixture of water, glycerin and formalin, and the preparation is covered and 

 cemented. Such preparations may be studied with the immersion lens. 



When the filariae are too small to be isolated, it is best to leave them in the midst of the detritus, and to stain 

 them as follows : — 



1. Allow them to dry on the slide. 



2. Fix with 95 per cent, alcohol, 1 to 2 minutes. 



3. Place in water a few minutes. 



4. Bohmer's haematoxylin, 1, 2 or 3 minutes, according to the intensity of the stain desired. 



5. Wash in running water, 3 to 5 minutes. 



6. Watery -01 per cent, solution of eosin, J to 1 minute. 



7. Wash in 95 per cent, alcohol. 



8. Dry with paper. 



9. Oil of cloves, 2 to 3 minutes. 



10. Xylol. 



11. Balsam. 



The above technique may appear complicated, but it may be carried through in 8 to 10 minutes. Without 

 staining, the filariae, when they are too small or too few, may escape observation. 



The dissection above described is not a careful dissection of the insect, but should be considered rather as a 

 coarse fragmentation into sections as follows : — The stomach, intestine and ovaries in one piece ; the thoracic 

 muscle in four or more bundles ; and the head and mouth parts. Care should be exercised not to lose a single 

 fragment. 



A somewhat similar paper is that by Ashburn and Craigi on the development of a 

 human blood filaria F. philippinensis in G. fatigans. They summarise the changes as follovvs : — 



In from 14 to 15 days the development is complete and the filaria has passed into the labium of the 

 mosquito ; the sheath of the embryo is lost in the stomach and the worm penetrates the stomach wall and reaches 

 the muscles of the thorax where most of the developmental changes occur ; during this period of time the filaria 

 has increased in length from 0-32 millimeter to as much as 2-20 millimeters, and in breadth from 0-0065 to 

 0-02 millimeter ; it has developed a well-marked intestinal canal, divided into oesophagus and intestine, a well- 

 defined anus and three papillas which are situated at the end of the tail ; the mouth appears to be simply a 

 circular cavity having no distinct lips. Development, so far as the morphology of the worm indicates, appears to 

 be complete at about the eleventh day, the only changes occurring after that being a lengthening and narrowing 

 of the filaria, which enables it to enter the labium of the mosquito. F. philippinensis does not seem to be 

 pathogenic. 



Fulleborn'2 has conducted an able research on the transmission of Filaria immitis of the 

 dog by certain mosquitoes, notably Anopheles viaculipcnnis and Stegomijia calopus. He has 

 shown the important influence of humidity and temperature on the act of transference of 



' Ashburn, P. M., and Craig, C. F. (March, 1907), "Observations upon Filaria philippinensis Development 

 in the Mosquito." Philippine Journal of Science, p. 1, Vol. II. 



■■' Piilleborn (1907), " Uebertragung von Filarienkrankheiten durch Mucken." Arch. f. Sch. u., Trnp. Hyg., 

 t. XI., No. 20. 



