250 



HARDWI CKE ' S S CIE NCE-GO SSI P. 



living ones, I attribute this convexity to endosmose, 

 due to the preservative solution in which they were 

 probably kept. During the present year I have found 

 three or four living specimens, and all these were rather 

 flat and wrinkled, just like Trombidium holosericeum. 

 Mr. Cambridge says that the "mouth parts are 



apparently very mi- 



Fig. 190. — Didactyle tarsus of 

 mature mite (highly magnified). 



nute, and concealed 

 in a deepish circular 

 cavity at the extremity 

 of the forepart." He 

 also says that the 

 structure could not 

 be ascertained by the 

 magnifying power at 

 his disposal. I there- 

 fore thought that it 

 would be acceptable 

 to some of your 

 readers to have a 

 sketch of these mouth parts, which are indeed very 

 remarkable, beautiful, and entirely different from 

 any other mite, whose mouth I have had the op- 

 portunity to examine. At first sight the creature 

 appears to have no mouth organs ; there is, how- 

 ever, on the under side of the forepart, a pit, or 

 depression, and when the mite is placed in a com- 

 pressorium, and graduated compression applied, the 

 proboscis emerges by degrees. Fig. 187 is a drawing 

 of these parts when partially protruded ; and fig. 188 

 the same after sufficient pressure has been applied, 

 not only to completely evert the organs, but also to 

 separate the component parts ; the figures are suffi- 

 ciently clear without description. I found the mites 

 whilst searching for beetle-mites amongst moss, and 

 rubbish taken from the decaying roots of trees in a 

 fir plantation. 



In March 1878, I found what I now believe to be 

 the nymph of this creature ; it has six legs, and each 

 tarsus is supplied with three claws, the central one 

 being much larger than the other two. When I first 

 found it, I took it to be the nymph of a Trombidium, 

 and did not examine it sufficiently whilst it was alive. 

 It is a very curious circumstance that these mites 

 should have tridactyle tarsi when in the nymph stage, 

 and didactyle ones when fully developed ; whereas, 

 in many of the beetle mites, the nymphs have but a 

 single claw, and the perfect creature possesses three. 

 I send an outline sketch of the nymph, from one of 

 my mounts ; also the claws of nymph and perfect 

 mite, highly but equally magnified. 



Kirton Lindsey. C. F. George. 



COSSUS LlGNIPERDA AND LlTHOSIA QUADRA. — 



I took two cossus at sugar here on the 9th of August 

 last, and one rather battered female quadra, while 

 flying round a lamp-post, on the 14th of same month. 

 The latter is, I believe, generally considered a New 

 Forest specie?. — y. R. Edwards, Strcatham. 



ON THE SCIENTIFIC VALUE OF 

 MICROSCOPIC PREPARATIONS. 



THE following remarks in a letter of Dr. Pelletan 

 ("Journal de Micrographie," 3 e annee, No. 3, 

 p. 139) on microscopic preparations will be appreciated 

 by those who use the microscope as an instrument of 

 scientific research rather than a superior kind of toy re- 

 quiring the aid of pretty objects to make it interesting ; 

 and it may moreover console those who have neither the 

 leisure nor the manipulative skill to arrange diatoms, 

 butterfly scales, sponge spicules, &c, in elegant 

 patterns. The selection of Diatoms, Polycystins or 

 Foraminifera, when very scarce in a gathering is 

 perhaps desirable, and the preparer may always 

 learn more of the structure and contour of the objects 

 by selecting and transferring them to a clean slide 

 than by merely mounting them with the extraneous 

 matter contained in the gathering, but there is no 

 advantage in arranging them in elaborate patterns. 

 We will now hear what Dr. Pelletan says about them. 



"You complain, in your letter, of the little 

 scientific value of the majority of microscopic objects 

 prepared for sale, and you have good reason for 

 doing so. With the exception of a few these pre- 

 parations are insignificant. They are often very 

 beautiful in appearance, mounted on the choicest 

 glass in an irreproachable cell, with varnishes of all 

 colours, the labels of every shade, and are very 

 elegant to look at ; but the object they contain is 

 worthless. The preparations of diatoms are alone, 

 for the most part, satisfactory, often excellent, and 

 sometimes marvellous. All the world is acquainted 

 with the preparations of diatoms of E. Wheeler, 

 A. C. Cole & Son, and above all of J. D. Moller, 

 whose ' Typenplatte ' is a veritable chef-d'oeuvre of 

 patience and manipulation. Certain preparations of 

 cryptogamic botany are also of some value, as sections, 

 dissections, &c, of vegetable anatomy, thin cuttings 

 of dense substances, animal, vegetable, and mineral, 

 and particularly sections of wood are all very in- 

 structive, but of all other classes of preparations 

 whose nomenclature fills the catalogue, it is only by 

 chance one meets with an interesting slide. 



" From what you have said I perceive that you 

 are occupied with microscopic anatomy, and more 

 especially that of insects. But histological prepar- 

 ations, whether normal or pathological, whether of 

 man and other vertebrates, or of the invertebrates, 

 are precisely those of the least value. 



"Of the Arthropoda, among others, the preparers 

 limit themselves to amputated feet, heads, antennae, 

 tongues, stings, &c, mounted in balsam, and behold 

 the result. Others, more ingenious, mount large 

 insects or immense spiders entire, after having 

 emptied them of their contents, and these prepara- 

 tions have really a magnificent appearance. But, 

 alas ! the integument is all that has been preserved, 

 and the little that remains of the internal organs is 



