74 Miscellaneous. 



upper parts mixed with brown. Though this, therefore, seems to be 

 an adult bird, still the colours are not so pure and dark as in other 

 specimens which I have examined from the south of England ; and I 

 am inclined to consider it as an adult that has just assumed the ma- 

 ture plumage. Like the other terns it is a summer visitor to Britain, 

 and unlike them it frequents rivers, freshwater ponds, and marshes, 

 in preference to the sea-coast, breeding among the grass and rushes of 

 their borders, and feeding principally on the varied insect-food which 

 abounds there. 



It is described as being common on the marshes of Holland and 

 other northern parts of Europe, extending even as far as the Arctic 

 circle ; but in Britain it is found principally in the south-eastern di- 

 stricts of England, where it is now by no means so common as it 

 formerly was. It " is a rare bird in the north of England, and is not 

 found in Scotland." (Yarrell's Brit. Birds.) Jardine and MacGil- 

 livray both allude to it as not having been met with in Scotland', so 

 that, as far as I am aware, this is the first specimen which has been 

 described as occurring so far to tbe north in Britain ; and I am in- 

 clined of course to claim it for Scotland, as in pursuit of its insect 

 prey it hunted over both sides of the river Tweed, which there forms 

 the southern boundary of our ancient northern kingdom ! 



P.S. — I was informed by a friend at the meeting of the Society, 

 that a specimen of this bird had been shot some years ago in East 

 Lothian ; so there can be no doubt of its occurrence at least occa- 

 sionally in Scotland. 



On the Circulation of the Blood, and Nutrition in Insects. 

 By M. Emile Blanchard. 



It has long been known that silkworms fed upon leaves powdered 

 with madder produced rose-coloured cocoons, whilst those fed upon 

 leaves sprinkled with indigo produced blue cocoons ; but these larvse 

 had never been examined anatomically. At the scientific congress 

 held at Genoa a few years since, however, Prof. Alessandrini of 

 Bologna stated that he had detected the blue colour in the tracheae 

 of some silkworms which had been fed on leaves powdered with in- 

 digo. He brought forward this fact as being unable to explain it, 

 requesting his colleagues to repeat the experiment. M. Bassi, having 

 undertaken this work, announced the following year, that silkworms 

 which had eaten coloured substances certainly exhibited the same 

 colour in their tracheae, but that the colour was not in the interior of 

 the respiratory tubes, but rather between the membranes forming 

 their walls. 



When I became acquainted with these inquiries, they appeared to 

 me to be of too much importance to be allowed to pass without re- 

 petition. I therefore took a quantity of caterpillars, particularly 

 those of the peacock butterfly (Vanessa Io), and placed them in two 

 boxes, furnished with leaves, powdered, in the one with madder, in 

 the other with indigo. After continuing this diet for several days, I 

 dissected some of my caterpillars, and was convinced that some of 



