204 



HARDWICKE'S SCI ENCE- GOSSIP. 



ture from this rule, for the wedge runs off to a fine 

 point, and no appearance of the canal is to be seen 

 (see fig. 111). In another specimen the canals are 

 seen at regular intervals, but no woody wedges 

 whatever ; it has one continuous vascular cylinder, 

 as seen in the Dadoxylons (see fig. 110). In some 

 plants the woody wedges are very numerous, with 

 a very thin cellular tract between them ; in others 

 the wedges are few, with a broad cellular tract 



<tfo°o 



u O°°°:- 



Fi<r. 111. 



extending to the bark ; this difference in individual 

 plants shows a great tendency to variation. The 

 bark of the Calamite is very delicate, and explains 

 the reason why so few plants are found with traces 

 of the bark. 



A memoir has lately been read before the Royal 

 Society by Prof. Williamson on Calamitea ; the 

 subject is anything; but exhausted, and we may 

 look forward with interest to the publication of this 

 memoir. If circumstances permit, I will send, from 

 time to time, descriptions of the different known 

 fossil plants that I have met with in our coal seams. 



John Butterworth. 

 Goats Shaw, near Oldham. 



PROTECTIVE MIMICRY. 



THERE has been much written of late on the 

 subject of " protective mimicry," but the most 

 striking examples have been taken from exotic 

 species. A practical illustration of the working of 

 the same principle nearer home has recently oc- 



curred in my experience, and is perhaps worth 

 recording. If to outwit man be a proof of higher 

 art than to deceive birds, then the mimicry displayed 

 by some of our native species will compare advan- 

 tageously with the cases described by Wallace and 

 Bates. A few weeks ago, on a bright July day, 

 while sauntering along a Cambridgeshire lane, I 

 espied what appeared to be a very fine individual of 

 the wasp tribe sunning itself on the leaf of a sallow. 

 With this impression I should certainly have de- 

 clined a closer acquaintanceship, but having a friend 

 who is on somewhat intimate terms with the Hy- 

 menoptera, I felt a vicarious interest in the creature, 

 and determined to attempt its capture. Remember- 

 ing the provincial rhyme of the " harnet " that " sat 

 on a hollow tree," and what " a proper spiteful 

 twoad was he," I proceeded with caution. The 

 warlike insect showed no signs of fear at my nearer 

 approach, but significantly clapped its hand on its 

 sword, or, to speak less metaphorically, kept raising 

 its abdomen and elongating the anal segments, as 

 is the fashion among wasps, so unpleasantly sug- 

 gestive of a sharp weapon ready to be drawn from 

 its gilded sheath to resent affront — 



" Et seepe attollunt humeris, et corpora bello 

 Objectant." 



Being destitute of any entomologieal apparatus, I 

 had recourse to the simple expedient of trying to 

 envelop it in my pocket-handkerchief, which was 

 easily accomplished. On arriving home, my pri- 

 soner presented a strangely worn, shabby appear- 

 ance, and exhibited a mildness of demeanour which 

 caused me to examine him more narrowly, and I 

 then discovered how thoroughly I had mistaken his 

 name and maligned his nature. I had unwittingly 

 caught a very harmless and rather rare moth, one 

 of the Clear-wings, Trochilium (Spkecia) crabroni- 

 forme. I will only remark further, chat the close 

 resemblance of this species to a hornet, as indicated 

 by its specific name, is not confined to mere outside 

 show, but extends to its deportment. It acts in 

 character, the threatening movements of the ab- 

 domen exactly mimicking those of the restless, 

 irritable " tails " of the Vespidge proper. 



Manchester. R. B. S. 



Hairs of Sundew.— At page 212 of Science- 

 Gossip, for 1870, " W. W." desires to be informed 

 how he can prepare the beautiful glands on the 

 leaves of Droscra rotiaidifolia, so well figured and 

 described at page 111 of the same volume. I beg 

 to inform him that I have succeeded in preparing 

 the glands to show the spiral vessels, by soaking in 

 ordinary glycerine a few days, which extracts the 

 colouring matter ; and should he desire to preserve 

 them permanently, mount in glycerine jelly. — /. 

 Maughan, Barnard Castle, 



