106 



HARDWICKE'S SCIENCE-GOSSIP. 



from the head downwards, by which the blood, as 

 it is seen coursing its way from the heart iu one 

 direction and returning by another, is purified and 

 aerated. The blood is seen to move by a sort of 

 regular pulsation which can be counted. The 

 sooner after leaving the egg for observing this the 

 better, as the tadpole is very transparent during the 

 first two days. Before the fore-legs become visible, 

 there are two appendages in form of minute claspers, 

 one on each side of the mouth (6g. 7i, a), by which. 

 in absence of legs, they are enabled to hold on to 

 any substance, and even in those minute claspers 

 may be seen single corpuscles of blood passing and 

 repassing. These appendages disappear in four or 

 five days, when the rudiments of the fore-legs are 

 seen, at first as two small lumps, which soon 

 lengthen out, and three of the toes only appear at 

 first (fig. 74, b), but gradually the foot is developed 

 into its proper form. In this also the circulation 

 of the blood is seen, as also in every part of the 

 body, but especially in the branchiae, aud along the 

 whole length of the under part of the body, from 

 the tail up to the head (fig. 74, c). In about three 

 weeks the hind-legs make their appearance, and 

 vrhen three months old the young are about an 

 inch in length, forming a beautiful creature iu the 

 aquarium (fig. 75), the brauchiaj at this time having 

 the appearance of beautiful feathered plumes. As 

 the young newts swim through the water they wave 

 gracefully to and fro with the motion. The blood 

 being red imparts colour to the branchiae, and to all 

 the more transparent parts of the body. In course 

 of time the branchial tufts, and the large trans- 

 parent fin (fig. 74!,(/) gradually diminish, and entirely 

 disappear, the skin becomes thicker and darker in 

 colour, and finally the reptile is perfected. During 

 the breeding season the smooth newts are very 

 prettily marked ; the male, in particular, is beau- 

 tifully spotted and coloured ; but as soon as this is 

 over they cast their skins, and assume a dirty brown 

 colour. They cast their skins several times during 

 a month. Sometimes it is thrown ofi^ in patches, 

 at other times it comes off whole. 1 have one ciuite 

 perfect which I saw cast off, and have preserved it 

 between two pieces of glass. The skin begins to 

 come off at the head, and is gradually pushed down 

 towards the tail, and several times I have seen the 

 newt take hold of the tail end of the skin with her 

 mouth, draw it off, and by a few gulps swallow the 

 whole. The young newt casts its skin before it is 

 half grown. At the end of the breeding season, 

 that sort of curiosity, or apparent inquisitiveuess 

 manifested by them, as before stated, leaves them ; 

 they no longer take notice of any one prying with a 

 glass into their domain. The bright colours and 

 spots disappear, together with the wavy crest from 

 the back of the male. Both sexes change in their 

 appearance, so that during the winter months I 

 have been unable to distinguish the one from the 



other ; but now, in March, 1874, they have again 

 assumed the bright colours, and the male has again 

 his beautiful crest tinged with orange-colour. They 

 also again manifest their usual inquisitiveuess by 

 coming to the side of the aquarium whenever a 

 pocket lens is applied to examine anything in the 

 water. James Fullagae. 



Canterbury. 



ON MANIPULATION WITH CANADA 

 BALSAM. 



THE object of the present paper is not to revive 

 the recent controversy respecting the best 

 method of preparing and mounting microscopic 

 objects in Canada balsam, but to aid students who, 

 like myself, have been debarred from mounting as 

 much as they would otherwise do, from the difficulty 

 of avoiding air-bubbles in slides prepared with hard 

 balsam. I shall first detail the method of mounting 

 I have found by practice to be the best, aud then I 

 intend to state my objections to other methods of 

 preparation. 



The object must first be dried : this is necessary, 

 and the neglect of it frequently causes the " cloudi- 

 ness " often found iu slides that have been mounted 

 quickly. Objects may be dried in two ways : viz., 

 by immersion in alcohol, or by exposure to a current 

 of dry air : the first is by far the best. (See Davies 

 on Mounting, second edition, p. 9.) After the object 

 has been dried, it must be placed in benzole ; this 

 liquid is better for this purpose than spirits of tur- 

 pentine, for reasons hereafter mentioned. The 

 object of this soaking is to remove the air-bubbles 

 which are almost always to be found in objects. 

 This process will take from one or two days to 

 several weeks, according to the size, &c., of the 

 object. After the air-bubbles are thoroughly ex- 

 pelled, the object must either be touched with 

 blotting-paper or drained for a short time upon a 

 slide. Drop as much balsam diluted with benzole 

 as may be required upon the centre of a clean slide, 

 and then take the object with a damped camel-hair 

 pencil, or a pair of forceps, and place it (the object) 

 in the centre of the balsam. Then place the cover 

 on, taking care to have it in the centre, aud place 

 the slide on a thick plate of iron or brass, aud apply 

 heat, by means of a spirit lamp, to the under surface 

 of the plate. Care must be taken not to agitate 

 balsam, as this would injure the object. Put the 

 slide in a warm place to harden. Many advocate 

 baking in a slow oven, but this is often injurious 

 to objects, especially delicate ones. After the 

 balsam is hardened, the slide must be cleaned (if 

 care is taken iu the mounting, very little superfluous 

 balsam will be deposited on the slide), and a ring of 

 varnish put round the edge of the cover by means 

 of a turntable. The best mixture of this is the 

 balsam in which the object has been mounted, as of 



