116 THE CANADIAN NATURALIST. [March 



remaiued. Not being thoroughly persuaded in my own mind as 

 to its nature, from the peculiar situation of the organism — it being 

 attached not to the leg, but impaled on the spines of the tibioe 

 and twise, also on the tips of the imgues, — it appeared to me as 

 if the creature, in feeding or flying over some plant, had brushed 

 off" something like seeds or flowers, or some fungoid growth. With 

 a view to find out its real character, I sent a mounted slide to 

 Mr. M. C. Cooke, the Editor of Science Gossip, and author of 

 " An account of the British Fungi," also of '' Microscopic 

 Fungi," for his opinion. He very kindly returned me the follow- 

 ing answer in the pages of the Science Gossip : " The supposed 

 fungus on the legs of Papilio asterias is not a fungus at all, but 

 pollen masses from some species of Orchis.'' 



Before receiving this answer, however, I had determined for 

 myself what the supposed fungus was. A friend having remarked 

 that he had captured some large flies with their legs covered with 

 a peculiar looking substance, I desired him to let me have a few 

 specimens, together with a specimen of the plant on which he had 

 taken them. The latter proved to be the milk weed, or wild 

 cotton Axlepias cornuti. On examination, I found the pollen 

 masses to be identical with those on the legs of the butterfly, 

 and that they (the pollen masses) belong to a species of the genus 

 Axlepias, and not to a member of the family Orchidaceae. 



This is another instance of the uses of insects as fertilizers of 

 plants. A. s. R. 



Microscopic Examination of Dust. — An ingenious appa- 

 ratus is figured in the monthly Microscopic Journal for collecting 

 atmospheric particles, contrived by Dr. Maddox ; the results are 

 also figured from micro-photographs. Dr. Maddox says: — 



" Dr. Tyndall has shown us that organic matter may escape 

 destruction to a great extent when air is drawn somewhat slowly 

 ' over fragments of glass, wetted with concentrated sulphuric 

 acid,' also ' over fragments of marble, wetted with a strong solu- 

 tion of caustic potash,' or when 'permitted to bubble through 

 the liquid acid and through the solution of potash,' and likewise 

 when rapidly passed through a red-hot platinum tube, containing 

 a roll of platinum gauze Valuable as these observations are in 

 themselves, we are but little nearer the chief question, which is 

 left open as to the vitality of such organic particles, or their rela- 

 tion to disease. 



