171 
Observations on the various Insects 
Fresenius, and to calculate the oxide of iron from the differ- 
ence. 
I'he experiments that have been brought forward in this paper 
will, we trusts be sufficient to establish a well-grounded con- 
fidence in the results of our analyses of plar.t-ashes published 
in this and former Journals of the Society. We have candidly 
acknowledged those particulars in which they are open to objec- 
tion, and feel that our assertion of their general accuracy will, on 
that account, be more readily received. 
VII. — Observations on the Natural History and Economy of 
various Insects affecting Carrots and Parsjiips : including 
Plant-Lice, the Maggots of Flies, the Caterjnllars of Moths, 
^c. By John Curtis, F.L S., Corresponding Member of 
the Imperial and Royal Georgofili Society of Florence; of the 
Academy of Natural Sciences of Philadelphia, iScc. 
Paper XIV. 
A s the tap-rooted vegetables are likely to become of more im- 
portance in field culture, both as food for cattle and man, an 
acquaintance with the enemies which assail and injure the carrots 
and parsnips must not be neglected, for such knowledge is 
actually necessary to their successful cultivation. As far as my 
own experience extends I am convinced that the parsnip is one of 
the best substitutes for the potato, not only as regards its nutritive 
qualities, but its produce also ; * and when a taste for it is once 
acquired, it becomes a most agreeable culinary vegetable : it is 
also sufficiently solid to satisfy hunger, and it is gently aperient. 
The greatest objection appears to me to be the length of time it 
occupies the ground, as parsnips keep best in the earth ; but 
this inconvenience, as far as the cottager is concerned, might be 
remedied by lifting the roots when full grown, about Christmas, 
and packing them vertically, close together, in some spare spot, 
from whence they could be drawn as they were wanted. 1 am 
also pretty certain that it is desirable to vary the vegetables which 
so largely contribute to the support of the labouring classes; for 
I have strong reasons for believing that potatoes, or any other 
vegetable, eaten" day after day, will not conduce to health and 
strength as the use of three or four different sorts will alternately : 
the culture, therefore, of broad and scarlet beans, Jerusalem 
artichokes, and parsnips, would make a wholesome, agreeable. 
* Vide Col. Le Couteui-'s valuable remarks in the ' Royal Agrie. Jounia], 
vol. i. p. 410, and Diekson's ' Piactical Agriculture,' vol. ii. p. 71B. 
