230 



HARDWICKE'S SCIENCE-GOSSIP. 



through a variety of erratic movements, strongly 

 suggestive of play. Even the solitary land tortoises 

 will, when they meet, gently touch their noses 

 together, and go through other movements suggest- 

 ing the expression of ideas to each other. Indeed, I 

 have never seen any animal as high as, or higher in 

 the scale of development than fishes, that did not 

 possess means of communication of ideas to its 

 fellows. I know not in what other way to explain 

 very many of the acts of these animals. To 

 return to the turtles. In May, 1881, my first 

 specimen of Muhlenberg turtle was kept in a small 

 vessel of water, for several days, in a darkened room. 

 Twice, while in the room, I heard it utter a shrill 

 note, which may be represented by the syllables 

 prcc-cdk, twice or thrice repeated ; Ihe last time less 

 distinctly than the previous utterances. To make it 

 the more certain that the first utterance was not 

 wrongly attributed to the turtle, I caused a ray of 

 light to be thrown upon the vessel containing the 

 animal, and I remained in the dark, but quite near at 

 hand. I could plainly see every movement of the 

 turtle, but do not think I was seen by it. After the 

 lapse of half an hour after the first utterance heard, 

 I saw the turtle come to the surface, and crane its 

 neck as far out of the water as possible. Opening its 

 mouth widely, it made the same utterance, and 

 repeated it, after an interval of probably ten seconds. 

 The sound was different from that of the snapper, 

 but the movements accompanying the utterances 

 identical. Since then, I have not been able to detect 

 any evidence of vocal powers ; but it must be borne 

 in mind, that in my subsequent studies of these 

 turtles I had several associated ; and if, as I 

 suppose, the note I heard is really a "call," then 

 it would only be uttered by solitary individuals, 

 when in search of a mate. 



Early in summer, if at no other time, the voice 

 ol the turtle is heard in the land. 



Charles C. Abbott, M.D. 



MICROSCOPICAL PAINTING. 



IN the January and February numbers of Science- 

 Gossir, are some observations of mine on this 

 subject. I now append an experience of some im- 

 jjortance. 



An object for drawing should be magnified to show 

 all the parts necessary for its elucidation, in fact, to 

 understand it as a whole ; and, as a rule, it should 

 occupy the entire field of vision. It sometimes, how- 

 ever, happens that many elongated preparations, as 

 for instance, the tongue and appendages of a bee, or 

 a double-stained section of a botanical specimen 

 cannot without reducing the magnifying power to a 



useless attenuation be included in a circle, as recom- 

 mended in a former paper, except at the loss of 

 considerable and important detail ; in such cases the 

 circle must be abandoned and the drawing made in 

 parts, by shifting the position of the object until the 

 whole is combined on the paper. This is attended with 

 some difficulty, in the management of the camera 

 lucida, but can be overcome in the following manner : 

 Having an elongated object, which cannot be seen in 

 its entirety in one field of view, the process is, to 

 draw the outlines and salient positions of one end, or 

 half-marking two prominent points on the paper 

 corresponding with two places in the subject ; these 

 positions are easily remembered. The object is then 

 moved, by the stage adjustments, upwards or down- 

 wards, as the case may be, until the other portion is in 

 the field. The marked points are coincided, by shifting 

 the drawing block, and the remainder of the outlines 

 finished ; the minute details of the drawing, and 

 painting, afterwards continued from the object itself. 

 By this method, the camera lucida may be used with- 

 out difficulty with four combined fields of vision, 

 and the various parts of the object so fitted as to result 

 in a drawing of considerable dimensions, perfectly 

 true in its contours. Botanical sections and elongated 

 parts of insects, under fairly high powers, may thus 

 be mapped out with all the details exhibited in their 

 relation to each othei". 



For good artistic work the importance of double 

 illumination cannot be too urgently advocated. Many 

 beautiful objects are often unappreciated from de- 

 ficiency, or inapplicability of the light used to 

 exhibit them. It is never more exemplified than in 

 the combined use of the paraboloid reflector and side 

 speculum, with a class of objects lately introduced, of 

 parts of insects mounted in fluid without pressure, 

 avoiding the disturbance of the more delicate 

 tissues. Many parts of such preparation are necessarily 

 opaque, which is rather an advantage from an art 

 point of view, as, by force of contrast, their density 

 aids in giving a most beautiful appearance to the 

 more transparent structures ; nothing being crushed 

 or distorted, all is /;/ situ. These preparations im- 

 mediately awaken the mind to the impossibility of 

 properly seeing, or revealing them, by the ordinary 

 reflected light from the mirror. The head and ad- 

 joining parts of the male wasp prepared in this 

 way by Mr. Enoch is singularly fine, and a case in 

 point ; with the paraboloid beneath the stage, and the 

 side speculum above, a combination of form and 

 colour is seen, of surpassing beauty. The light from 

 the speculum touches the opaque parts with reflec- 

 tions revealing the most exquisite tints of a metallic 

 appearance, while the paraboloid beneath shows, in 

 actual perspective, the wonderful parts beyond in all 

 their natural colour, and bathed in light. 



E. T. D. 



Crouch End. 



