THE AMERICAN MONTHLY 



[May, 



carefully spreading them out with a 

 needle on the slide, then search for 

 the archegonia. It consists of two 

 portions, the lower ovate (fig. 13, 

 a) , and the upper, or neck, of arche- 

 gonium (fig. 13, b) . The archego- 

 nium is ruptured by the fertilized 

 oosphere, often in such a way that, 

 while the lower part remains as a 

 sheath, the neck is elevated as a cap 

 now known as the calyptra on the 

 top of the theca or capsule. On 

 the top of the theca is a small lid, 

 or operculum. When this is re- 

 moved, the inouth or stoma is seen 

 surrounded by a beautiful series of 

 teeth called the peristome (fig. 14) ; 



Fig. 14. 



the stalk supporting the theca is the 

 seta. Now prepare a section of 

 the theca. Fig. 

 15 «• is the colu- 

 mella, and fig. 15 

 /) the operculum, 

 beneath which is 

 the peristome. 

 When the spores 

 germinate its ends 

 out a fi 1 i f o r m 

 body, known as 

 the protenema, or 

 pro embryo, on 

 which the young 

 plant is developed. 

 The I'oot hairs, 

 which will be 

 found at the base 

 of the stem and 

 w^hich take the 

 Fig. 15. place of true roots. 



are called i-hizoids, play an important 

 part in the economy of these plants. 

 Detached leaves of the Funaria placed 

 on moist soil will produce the pro- 

 tenema. 



J. F. R. 

 o 



The New Objectives and Oculars. 



Since our last issue, in which a 

 notice of the new objective and ocu- 

 lars by Mr. Zeiss was published, we 

 have received the advance sheets of 

 the Jour u. Royal Micr. Soc.^\\'\\\\ 

 an article giving moi"e detailed in- 

 formation concerning the subject, 

 from which we quote the following 

 paragraphs : — 



' For some months past it has been 

 known that we were on the eve of 

 an important advance in objectives, 

 depending mainly on the elimination 

 of the secondar}- spectrum, leaving 

 only a small tertiary spectrum .... 



' Two objectives have now been re- 

 ceived in this country, and their ex- 

 amination has fully borne out the ex- 

 pectation formed of them, and has 

 shown that however trifiing the im- 

 provement might at first sight be 

 thought to be on theoretical grounds, 

 it is very distinctly appreciable, so 

 that the high power work of the fu- 

 ture will almost necessarily be done 

 with these glasses. 



' The objectives in question are both 

 \ inch. The special point in their 

 construction is that they are made of 

 new kinds of optical glass, which 

 Prof. Abbe and Dr. Schott have 

 been working for the last five years 

 to perfect. The objectives are com- 

 posed often single lenses, combined 

 to five separate lenses, with a single 

 front lens. Their working distance 

 is 0.35 mm., and in order to secure 

 this the aperture is limited to 1.40 

 N.A. With the length of tube en- 

 graved on the setting (taken from 

 the nose-piece to the eye-lens) , the 

 objectives have their best correction 

 for a cover-glass of 0.16-0. 18 mm. 

 Much thinner covers require a length- 

 ening of the tube by 10-35 mm. fur- 

 ther. They are very sensitive in re- 



