EXAMINATION OF MOULDS 73 



the construction of the microscope will admit of this being placed 

 on the stage. 



By the following method there is but little difficulty in at once 

 recognising the various species, and a beautiful demonstration is 

 given of the hyphae with interstitial cells, and germinating conidia 

 of the Oidium lactis, the conidiophore and sclerotium of the 

 Pencillium glaucum, or the ramified mycelium, sporangia, and 

 germinating zygospores of the various species of Mucor, without 

 disturbance of the growth. 



By means of a finely drawn pipette allow to fall upon the 

 centre of the mould colony a small drop of aqueous solution (i per 

 cent.) of eosin. It is necessary to exercise a little care in this, or 

 the liquid will at once run off the colony on to the surrounding 

 medium. Place carefully upon the centre of the drop a thin cover- 

 glass, and press in order to obtain close contact Remove the Petri 

 dish to the stage of the microscope and examine the margins of 

 the growth with a sixth objective. 



If the construction of the microscope will not allow examina- 

 tion on the Petri dish, or if a permanent specimen is desired, the 

 following method can be recommended : — Detach by means of a 

 pair of fine pointed forceps a portion of the young growth, holding 

 it by the base, and place it carefully on a slide. Place near it one 

 drop of ammoniated alcohol, and bring this in contact with the 

 specimen by means of a finely pointed needle. The absorption 

 of the alcohol will allow the subsequent penetration of the tissues 

 by the liquids employed. Drop on to the preparation a small 

 quantity of Flemming's solution, and allow it to remain for four or 

 five minutes. Wash carefully with water, cover with a cover-glass, 

 and examine. 



To make a permanent preparation, replace the water with 

 glycerine by placing a drop of the latter at one side of the cover- 

 glass, and absorb the water from the other by means of filter 

 paper. Dry carefully with filter paper damped with alcohol, and 

 ring with paraffin. 



Flemming's Solution. 



Chromic acid, i per cent. . . . .15 volumes. 



Osmic acid, 2 „ . . . . 4 „ 



Glacial acetic add ..... I volume. 



Examination of milk for pus cells- 

 Place 10 c.c. of the milk to be examined in each tube of the 

 centrifuge (Fig. 13) and centrifugalise for two minutes. Pour off 



