192 



THE AMERICAN MONTHLY 



[October, 



cause many persons who have not 

 been accustomed to using micro- 

 meters regard it as a troublesome 

 proceeding. We are told in the books 

 to make one division of the stage- 

 micrometer correspond exactly with 

 a number of lines in the eye-piece, 

 which can be done by changing the 

 magnification by means of the draw- 

 tube. The object of this is to make 

 a certain number of divisions equal to 

 .CI or .001 of an inch. But practi- 

 cally it is a useless waste of time, for 

 it is of no consequence to us, for ex- 

 ample, whether four, or four and 

 a half, or four and a quarter divisions 

 represent a thousandth of an inch ; 

 what we want is the value of one di- 

 vision. 



The Huyghenian eye-piece is good 

 enough for all practical purposes, 

 although the Ramsden ocular is, in 

 some respects, better. The Jackson 

 eye-piece micrometer is preferred by 

 some to the simple ruled cover-glass, 

 because it is provided with a screw 

 movement to adjust the lines to the 

 object, but this can readily be done 

 by the stage movements, and the 

 disc of glass resting on the diaph- 

 ragm of the ocular is never in the 

 way, while it is protected from dust. 



The 



Internal Stellate Struct- 

 ures of Plants. 



Mr. Cox in his criticism of my re- 

 marks on the Internal Stellate Struct- 

 ures of the Nymphaeacae, published in 

 the September number of your Jour- 

 nal, makes the following statement: — 



" One thing, however, seems to me 

 beyond doubt, that in the leaf of 

 ^^ Nymphcea or Nuphar the principal 

 " part of the internal hairs are plant- 

 "ed in the uppermost parenchymal 

 "layer." 



This assertion I can not let pass 

 without challenge. 



After examination of a great num- 

 ber of recently made preparations of 

 the white, yellow and pink varieties 

 of the plants in question, I am un- 



able to discover anything which would 

 go to show that the " internal hairs" 

 are planted in the upper parenchy- 

 mal layer. 



Those Microscopists who have, by 

 chance, come in possession of some 

 of my preparations of Nymphosa, 

 will be able to decide by vision the 

 merits of the question at issue, and 

 without vision it cannot be decided 

 by discussion. The stellate struc- 

 tures have their starting point in the 

 perenchymal layer next below the 

 epidermis; some of the branches row 

 upwards to the epidermis, where, 

 when by it arrested in their elonga- 

 tion they divide in two, and when the 

 branches do not traverse the layer 

 completely, they remain pointed. 



The epidermis may be removed, 

 or what amounts to the same thing, 

 the parenchymal layer may be re- 

 moved from the epidermis without 

 a single star remaining attached to 

 the epidermis ; the external hairs of 

 plants cannot be removed in that 

 manner from the epidermis : they 

 are part of it. 



I would further call the attention 

 of observers to the fact that the vas- 

 cular system is quite sparingly repre- 

 sented in the leaf of the plants under 

 consideration, and it requires a long 

 search to discover traces of it in sec- 

 tions of the petiole. Some homologues 

 or equivalents must necessarily exist ; 

 the stars and the elongated fibres offer 

 themselves as such, without, in my 

 opinion, straining the argument. 



J. Kruttschnitt. 



EDITORIAL. 



American Society of Microsco- 

 pists. — Dr. George E. Blackham, the 

 President of this Society, has issued 

 a circular to the members, the pur- 

 pose of which is to enlist the earnest 

 cooperation of the members in mak- 

 ing the meeting at Elmira a success. 

 We have no doubt but that meeting 

 will be a good one, and, for the satis- 



