770 SUMMARY OF CURRENT RESEARCHES RELATING TO 



for popular exhibition, nothing could be more beautiful, when properly 

 displayed, than the very common " moulds," which were universally 

 familiar, and, indeed, only too often more familiar than welcome. But 

 there was considerable difficulty in mounting them, or even in preparing 

 them for exhibition as temporary mounts for transmitted light. This 

 was due partly to the fact that the spores were very readily shed, and 

 the whole plant disorganised, in the dry air of a room, and partly to the 

 difficulty of getting water to penetrate effectually among the hyphse. 

 Some years ago a friend had sent him a bottle of fluid and some speci- 

 mens of micro-algae preserved in dilute spirit, with the directions, 

 " Wash out the spirit and mount in the fluid." The result was very 

 satisfactory, staining and permanent preservation being effected at the 

 same time, with only one medium. The method was found to answer 

 equally well with fungi, the only difficulty lying in the preliminary 

 process. The fluid consisted of glycerin to which an alcoholic solution 

 of Hoffman's blue was added in sufficient quantity to obtain the desired 

 tint. It was essential that the blue should be of the best quality if 

 permanent results were wanted. Methylen-blue could be used as a 

 substitute, but the colour faded quickly. 



The method of mounting was as follows : — A drop of alcohol of 

 strength 80 p.c. to 90 p.c. was placed upon a glass slip. A small portion 

 of the fungus was placed with as little disturbance as possible in the 

 alcohol, which at once penetrated the fungus. The alcohol quickly 

 evaporated and another drop was then placed on the object, which was 

 left to soak in it for about a quarter of an hour. Then a drop or two 

 more of dilute spirit, say 25 p.c. strength, was added. When this had 

 penetrated the specimen, the slide was left undisturbed for several 

 hours, care being taken to insure that the fluid did not evaporate 

 altogether. By these processes the initial difficulty of the resistance 

 to wetting was overcome, and at the same time the tissues were fixed 

 and hardened. After some hours (or sooner if convenient) the spirit 

 was washed out with distilled water. This was done on the slide with a 

 camel-hair brush, with which some of the superfluous spores were at 

 the same time removed. While the object was still wet a drop of the 

 coloured glycerin (diluted if the object is a delicate one) was placed on 

 the fungus and allowed to soak in thoroughly. It was a good plan at 

 this stage to put the slip away in the cabinet for a time. Finally, the 

 specimen was arranged under a Microscope, the diluted glycerin with- 

 drawn with a brush, and a drop of glycerin of full strength substituted. 

 The cover-glass was then placed in position and cemented down. Unless 

 the object was thick no cell was required. The algse could be treated 

 in the same manner, but were much easier to deal with, as they did not 

 require such delicate manipulation in the early stages. 



Apparatus for Staining simultaneously Numerous Sections.* — 

 The apparatus devised by L. Neumayer consists of two hoops, a and b, 

 united by cross-pieces e, e (fig. 182). The hoops, which are 2-9 cm. 

 high, are 7*9 cm. apart, a distance which easily admits the insertion of 

 the ordinary slide. Upon the cross-pieces rest the two rings d and e, 



* Zeitschr. wis*. Mikrosk., xxii. (1905) pp. 181-5 (1 fig.) 



