MUCOR AND PENICILLIUM 167 



PRACTICAL WORK. 



MucoR. 



(i) Examine with a hand lens the young mycelium of Mucoy 

 growing in gelatine containing some nutritive substance such as 

 raisin-extract. Cut out a very small portion of the gelatine 

 containing the mycelium near its edge, and place it in a large 

 drop of water on a slide till it becomes nearly liquid. Then 

 put on a coverslip : squeeze it gently and look for hyphae, first 

 with the low and then with the high power of the microscope. 

 Draw a portion of a hypha, including its tip, under the high power, 

 showing wall, protoplasm containing vacuoles, which are smaller 

 towards the tip. Note the absence of cross walls. 



(2) Examine an older plant (if possible growing in a watchglass 

 of gelatine) which has produced sporangia — first with a hand 

 lens. Then place the watchglass on the stage of the microscope 

 and focus slowly down with the low power. In this way an 

 excellent idea of the habit of growth of Mucor is obtained. Note 

 the spherical sporangia of different ages borne on the summits 

 of the sporangiophores, and the branching mycelium below. 



Mount some of the mycelium, carefully removed in a drop 

 of methylated spirit to get rid of air, and add a drop of dilute 

 glycerine. Find and draw various stages in the development 

 of the sporangia. 



(3) Examine a still older plant with mature sporangia. Mount 

 some as in {2) and draw stages before and after bursting. Note 

 the columella. Draw also a few spores. 



(4) Examine a culture or a prepared slide showing zygotes. 

 Look for and draw stages in conjugation and the formation of 

 the zygote. 



Penicillium. 



(5) Examine Penicillium (Blue Mould) in the same way as 

 Mucor — ^first in situ with the branched conidiophores rising into 

 the air. Examine the brushes of radiating conidiophores under 

 the low power. Examine part of the vegetative mycelium in 

 gelatine squeezed out in water, and note the segmented mycelium 

 with pale blue-green cytoplasm. Draw two or three segments 

 under the high power. 



Carefully remove some conidiophores, dip them in a drop of 

 spirit, and mount in dilute glycerine ; examine under the high 

 power the chains of conidia and their mode of formation by 

 budding from the tips of the conidiophore branches. 



