548 



Journal of Applied Microscopy. 



Affected portions of leaves and stems should 

 be fixed in chromo-acetic acid and cut in paraffin. 

 Safranin-gentian violet-orange seems to be the best 

 stain for differentiating the nuclei. 



It is more difficult to get good sections of the 

 plant in the oosporic condition. The oosporic 

 phase of Cystopus bliti is easily recognized on 

 Amarantus, where the oospores may be seen with 

 the naked eye by holding the leaf up to the light. 

 While better nuclear staining can be secured with 

 chromic or Flemming material, it will be found 

 somewhat easier to cut material which has been 

 fixed in picric acid (1 per cent, solution in 70 per 

 cent, alcohol). Celloidin sections, stained in Dela- 

 field's haematoxylin, can be recommended for show- 

 ing the position of oogonia and antheridia, although 

 such sections are too thick to give satisfactory views 

 of the nuclei. 



( To be continued. ) 



-'euif ytpp A^jc 



Fig. 27. Cystopus candidus on 

 Capsella. 

 Trans, sec. of a blister on the leaf. 

 X 255. From a preparation fixed 

 in Flemming's fluid and stained in 

 safranin-gentian violet-orange. 



A Convenient Method of Numbering Slides in a Series. 



In cutting sections in series, their number is often so great as to run over a con- 

 siderable number of slides. It is well, therefore, to designate the slides in some way 

 which will not be affected by the reagents through which they are passed. A con- 

 venient method is as follows : After the sections have been placed on the slides 

 with the fixative beneath, number them with a pencil 1, 2, 3, 4, etc., on the ground 

 glass edge at the end of the slide. As this edge is too narrow for ordinary 

 figures, make as many little lines across it as there are units in the number. If 

 this is larger than five, a space might be left between each group of five marks 

 to aid in reading them. This method may also be used to show upon which side 

 the sections are. For instance, if when the slide is held in the hand the sections 

 are on the upper side, and the numbers are placed on the end, nearer the left- 

 hand corner, the sections will always be above when the slide is held in the 

 same relative position again. The numbering of slides in this way is very easily 

 done, and the writer has found common pencil-marks to be unaffected by the 

 ordinary reagents used in sections. Ruth M. Huntington. 



Smith College Zoological Laboratory. 



