84 manipulation 



Note on Manipulation. 



I )ri«(l specimens of Uredinales keep most of their characters 

 unchanged for an unlimited time, but the colours fade except 

 those of the teleutospores. The only two difficulties found in 

 examining them arc in regard bo the markings on the outer 

 surface of the spores, and the number of germ-pores. For the 

 first, different methods succeed in different cases, but the finer 

 markings can usually be seen by examining the spores under a 

 one-sixth inch in air. or in water after squeezing ou1 their 

 granular contents by tapping or pressing hard upon the cover- 

 glass. For the second, boiling for about a minute in a drop of 

 lactic acid, on a glass slide over a spirit-lamp, is the best course, 

 although expulsion of the contents under pressure frequently 

 brings the germ-pores into view: in fact so plain do they often 

 become that they can be photo-micrographed with ease. Boiling 

 in lactic acid also restores old collapsed spores to their former 

 size and plumpness. 



The preparation from which Fig. 37 was drawn was 

 obtained in the following way: lav the side of the leaf opposite 

 to the sori in a thin layer of 5 , KOH solution for an hour or 

 so, then reverse and brush or scrape away the softened tissue 

 as far as possible ; on mounting the remaining surface, epidermis 

 upwards, in glycerine and water, the arrangement of the parts 

 can be clearly seen. 



If it is wished to observe the germination of the spores in a 

 hanging drop, almost any uredo will serve; for teleutospores 

 Puccinia Malvacearum and for secidiospores sEcidium Ficariue 

 are usually the most handy. One of the best double stains 

 to use is Diamant Fuchsin and Light Green; the former stains 

 the nuclei red and the latter the cell-walls green. Stain heavily 

 with the former and wash out with alcohol till the desired tint 

 is arrived at; then use the Light Green dissolved in clove oil. 



