52 



HARDWICKE'S SCIENCE-GOSSIP. 



[March I, 1S70. 



enlarge the anal orifice. After having extracted all 

 the moisture and intestines, insert in the aperture a 

 bent glass blow-pipe, having a bulb in the middle, 

 and inflate the larva over a spirit-lamp, having a 

 flat piece of zinc fixed over the flame. Holding the 

 tube so that the larva does not touch the zinc plate, 

 blow gently, until it is quite dry and hard. This 

 requires great care, as it is liable to scorch ; and, if 

 the skin be only partially dry, it will, although 

 apparently finished, become indented or depressed 

 in those places where it is not thoroughly hardened. 

 To ascertain if the operation be complete, cease 

 blowing, and draw in the breath gently ; when, if 

 the larva is not dry, it will shrivel up, and must be 

 inflated again immediately ; if, on the other hand, it 

 is dry, it will remain distended to its natural size 

 and appearance. To prevent the head from being 

 extended too much, dry all the body except the first 

 and second segments, take the larva away from the 

 spirit-lamp, and press the head into its natural posi- 

 tion, afterwards drying it at some distance from 

 the flame, without blowing through the tube. If 

 the larva require colouring (as almost all green 

 larvae do), some very finely powdered dry colour 

 (rather darker than the original colour of the larva) 

 must be introduced into the skin after it is 

 thoroughly dry. To get the colour evenly on the 

 inside of the skin, it must be rolled about in the 

 hand. In order to direct the heat on to any 

 particular place, a small hole (about the size of the 

 head of a pin) should be made in the centre of the 

 piece of zinc. This will be found to be particularly 

 useful, when finishing the head of the larva, as 

 above described. The object of having the glass 

 tube bent is, that the head is then above the level 

 of the flame; and the bulb is to prevent any 

 moisture from the mouth running down the tube into 

 the inside of the larva. I generally put a piece 

 of blotting-paper in the mouth-piece of the tube. 



The inflation while the larva is over the lamp 

 must be kept up without intermission. This is 

 very easy after a little practice, and does not cause 

 any exertion, as the breathing is carried on through 

 the nose. 



A larva should be kept without food for a day 

 before being killed, as it is almost impossible to 

 extract the food that it has just eaten ; and, after 

 the larva is dried, this shows in an ugly black patch 

 just behind the head. 



Very frequently it occurs, that, while blowing, 

 the larva will slip off the tube ; this can be pre- 

 vented by tying a thin piece of cotton round the 

 end of the tube and the last pair of claspers. It is, 

 however, as well, if possible, to dispense with tying 

 the larva on the tube, as it very often distorts the 

 shape of the last segments. 



The best larva for a first experiment is one that 

 has no bright colours and is not hairy ; such as 

 Noctua xanthographa. 



The reason for putting the larva in pyroligneous 

 acid or a solution of alum is to harden the skin, so 

 that it may not be inflated too much ; and, if hairy s 

 to prevent the hairs from falling out whilst being 

 handled. 



When preserving a brightly-coloured and hairy 

 larva, such as Bombyx Neustria, Igenerally starve it 

 until it is nearly dried up, and then kill it and take 

 the inside out. In conclusion, I would remark that 

 some amount of patience is requisite to ensure 

 success. Any further particulars or explanations 

 that may be required I shall be most happy, 

 if possible, to afford. — Entomologist's Monthly 

 Magazine. 



ON POLLEN* 

 By Chaeles Bailey, Esq. 



HAVING recently examined the pollen of 

 several thousand species of plants, I am led 

 to think that the characters presented by these 

 grains might prove useful as a means of differentia- 

 tion in allied species ; my researches, however, have 

 not been sufficiently extensive to form any positive 

 conclusions ; but as leisure permits I hope to pro- 

 secute the subject further. In the meanwhile the 

 following notes are thrown out as indications of 

 some of the more noticeable distinctions to be drawn 

 from a careful comparison of these organs, and they 

 may serve to draw the attention of others to the 

 matter. 



There are four points, in one or other of which 

 pollen-grains of plants belonging to the same genus 

 may be found to differ from each other; viz., form, 

 markings, dimensions, and colour. 



1. Form. — It has long been noticed that certain 

 types of pollen are characteristic of the natural 

 order to which the plants which produce them 

 belong ; as for instance, the peculiar pitted poly- 

 hedral pollen of the Caryophyllacea, the spherical 

 spiny pollen of the Malcacea, the large triangular 

 pollen of the Onagracece, the peculiar pollen of the 

 Coniferce, or the elliptical pollen of the Liliacem and 

 other nonocotyledonous orders ; in fact, most orders 

 possess a type sufficiently marked to be character- 

 istic of each. This statement, however, must be 

 accepted with limitations ; the Composite, for 

 instance, have three or more well-marked types, 

 represented by the beautifully sculptured pollen of 

 the Chicory, the minute oval spiny pollen of the 

 Asters, Calendulas, Cacalias, &c. ; and another form 

 wholly destitute of spines, as in the Centaurea sca- 

 biosa. There are, besides, other natural orders 

 where similar variety occurs. 



But differences of form are met with in plants of 

 the same genus, by which the one species or the 



* Read at the Literary and Philosophical Society, Manches- 

 ter, Dec. 28th, 1869. 



