I 



23 



all sorts of microscopic crystals in plants are too commonly included 

 under the term "raphides" But this error is quite fatal to any 

 due estimate of their taxonomic value. Crystals of one form or 

 other are common, and often abundant, in plants that never pro- 

 duce any raphides at all. Hence we have had and still have end- 

 less ambiguity and confusion, which it is to be hoped that the 

 author's drawings and detailed descriptions, reproduced in the 

 'Science Gossip,' May 1, 1873, will correct in future. But, be- 

 Rides the vagueness of the current knowledge of the subject, a 

 prevailing cause of the difficulty in the acceptance by systematists of 

 the characters afforded by raphides, is the difficulty and extensive- 

 ness of the inquiry as to the value of such diagnoses. The question 

 first to be determined concerns the constancy of raphides or other 

 crystals in several single species of our native plants, at all periods 

 of their growth and in every soil or situation ; and then come the 

 wider researches as to the constant absence of the crystals from 

 other species, and the still more laborious task of carrying the 

 whole investigation throughout the Flora of the world. On this 

 last point the author's observations have been fragmentary only, 

 but they have been continued for many years on British plants, 

 with occasional elucidations by parallel examinations of exotic 

 species. Difficulties will often occur. Thus, after searching for 

 years for a plant of the Order Onagraceae devoid of raphides, it 

 was, seemingly, found in Montinia, but only to afford one of those 

 exceptions that best prove the rule, as this genus, though placed in 

 the Order Onagraceae by Lindley, has since been removed from it to 

 the Saxifragraceae. The angular minute crystals, about 1 -400th of 

 an inch long and 1 -'20000th thick, occurring for the most part 

 scattered here and there singly in the old leaves of Gentiana acaulis, 

 and some other plants, are not true raphides. 



April 11th, 1873. 



Apparatus for Drawing Microscopic Objects. — Colonel Horsley 

 exhibited for this purpose a very simple contrivance, which is 

 easily used and need not cost a shilling. It consists of a deal box, 

 four and a half inches sqxiare and nine inches in length, with a cir- 

 cular apertu'e at one end large enough to admit the draw-tube of 

 the microscope with the eyepiece attached, and at the other end a 

 square of ground glass of the same size as the box, the wood 

 having been removed for the purpose. To obtain the desired 

 image of the object the microscope is placed horizontally, with its 

 eyepiece end into the hole made for it into the box, when the ob- 

 ject is focussed and illuminated on the ground glass, and then very 

 easily drawn by hand. The whole apparatus is more fully de- 

 scribed in ' S'cience Gossip,' 1868, ^p. 236. 



Queen of the Honey -Bee. — Major Munn exhibited drawings in 

 illustration of the structure and functions of the oral apparatus of 

 the queen as compared with the corresponding parts oi the drone 



