HARD WICKE'S SCIENCE- G OSSIP. 



141 



wondered what was the use of the spikes projecting 

 rom underneath the different legs, but could not find 

 anything about it in any book or paper I came 

 across. A few days ago, while sitting near a window 

 and watching (with a pocket-glass) a gnat as it 

 crawled up and down the glass, I saw it place its 

 antennce between the spikes in question and its leg, 

 and draw it along and thus plume it. — Herbert H. 

 Clarke. 



"Aphides and their Monuments." — In the 

 October number of "Science-Gossip," page 236, is 

 a note of mine with the above heading. At its con- 

 clusion I asked for information from some of your 

 entomological correspondents, concerning the beauti- 

 ful and interesting objects described, but, alas ! got 

 none. One good old friend, however, to whom I had 

 written privately, and who is an excellent naturalist 

 and microscopist, knew nothing of the matter, but 

 set to work and soon referred me to Buckton's mag- 

 nificent monograph published by the Ray Society 

 (four large volumes, beautifully illustrated, and all 

 about a plant-louse, please ! ! ! *) and as, I take it, 

 there are many of your readers who know the happi- 

 ness of having a great deal to learn, or at least of not 

 knowing everything, I refer them to Vol. 2, page 85, 

 Plate 64 ; but as that book is not within everyone's 

 easy reach, I will tell, in short, what it says : — A 

 certain minute parasitic fly of the family Ichneu- 

 monidae pierces the body of the living Aphis and 

 deposits its eggs therein. The egg is hatched, the 

 grub thrives, and when full fed ' ' perforates the hard 

 aphis-shell at the belly and commences to spin a 

 double-walled tent between the space comprised by 

 the six legs of the insect. The floor of the tent is 

 attached to the leaf on which the aphis originally fed, 

 the web being carried up to its skin, which then 

 partially forms its roof. Subsequently the edge of 

 the web is reflected downwards so as to form a 

 chamber with double walls .... In this cocoon 

 the change into Pupa takes place ; and after an 

 interval of about nine days the winged parasite eats 

 its way out of the silken envelope .... Not un- 

 frequently the empty skin of the winged Aphis may 

 be seen mounted on the summit of one of these 

 parasitic cocoons." Instead of" not unfrequently," I 

 would say very frequently, judging from my experi- 

 ence of last year, and now is the time for searching 

 the sycamore leaves. In the same volume, page 236, 

 will be found an interesting description of the fan- 

 insect (the abnormal Aphis larva), which I alluded 

 to in your October number. The bundles of stalked 

 eggs are those of the lace-winged fly, more usually 

 found singly. — Thomas E. Amyot, Diss, Norfolk. 



* The notes of admiration were suggested by the good- 

 natured if rather contemptuous smile of a horticultural friend 

 who has no sympathy w;th plant-lice, but who saw the book 

 on my table. 



BOTANY. 



The Mexican Agave. — As to the Mexican agave, 

 concerning which a paragraph appears in the May 

 number of Science-Gossip, I have made inquiries 

 at Kew Gardens, and am told that in England this 

 plant does not flower till it is thirty, forty, or sixty 

 years old, that is, not till it has completed its growth. 

 When it is full grown it flowers. After flowering 

 the plant always dies, but new plants grow from the 

 base. The " report like a rifle-shot " is an exaggera- 

 tion, but each flower-bud as it opens makes a slight 

 noise of the kind, like ripe fuchsia-buds do when 

 pressed. This, in the agave, is caused, I am told, 

 by the fact that the bud before opening contains no 

 air, and it is the inrush of the air which causes the 

 noise. — Frank Sick, pin. 



Notes on the Additions to the British 

 Flora since the publication of the last 

 editions of Babington's Manual and Hooker's 

 Student's Flora. — I have been repeatedly asked, 

 and urged to give a list of the above additions, with 

 short characters to separate them from our other well- 

 known species. But they have become so numerous, 

 if we take in the hybrids and varieties, that it has 

 become no light task to compress such an account 

 into anything like a reasonable length. What I here 

 propose to do is to go through the principal additions 

 only, leaving out hybrids, and perhaps some varieties. 

 I would refer all those w.ho seek for further informa- 

 tion to the forthcoming supplement to the 3rd edition 

 of English Botany, edited by Mr. N. E. Brown of 

 the Kew Herbarium. Here the additions will be 

 figured and described fully, at the same time the 

 matter of the original work will be brought up to 

 date as far as possible. Good progress has been made 

 in the study of the distribution of our Flora since the 

 publication of the 2nd edition of Watson's Topo- 

 graphical Botany, and if some means could be found 

 to cheapen that work so as to make it accessible to a 

 larger number of our botanists, it would be a great 

 advantage. A large mass of additional matter has 

 been accumulated, especially as to Scottish botany, 

 and I should like to say that I should be glad to see 

 specimens of any species unrecorded for any county 

 in Topographical Botany. There is still much work 

 to do in this department of British Botany, as to 

 verification of doubtful localities, etc. ; while the 

 subject of the life-histories of our plants is hardly 

 yet touched. I have adopted the nomenclature and 

 sequence of the Sth edition of the London Catalogue 

 of British Plants as being available to all, giving 

 however, a second name where it seemed needful, 

 and to give more help. It will be seen that I 

 attempt no technical characters, but merely such as 

 are usable in the field, and what may be termed off- 



