ZTGOPHTTA. 129 



mounting some of the second collecting, here and there the formation 

 of resting spores may be observed. In all cases care must be taken 

 not to mount too great u, quantity of the material, nor to injure the 

 plants by rough handling. 



(e) In the study of Black Moulds it is mostly necessary to make 

 use of alcohol for freeing the specimens of air; afterwards they usu- 

 ally require to be treated with a dilute alkali, as a weak solution of 

 ammonia or potassic hydrate, which causes the hyphse to swell up to 

 their original proportions. 



(/) Cut a lemon in two, and, squeezing out most of the juice, ex- 

 pose the two halves to the air of an ordinary living-room or school- 

 room for a few days, when various moulds will begin to develop. 

 Under favorable circumstances Black Mould will predominate. It 

 can be told by its dark color and the minute round black spore- 

 cases on the ends of the erect hyphse. Mount a few hyphse (as di- 

 rected io e above) and examine hyphse, spore-cases, and spores. 



(g) Moisten a piece of perfectly fresh bread, and' then sow here and 

 there on its surface a few spores of Black Mould; cover with a tum- 

 bler or bell-glass. In a few hours a new crop of Black Mould will 

 begin developing. 



(A) The most common Black Moulds are species of the genus Mucor. 

 M mucedo and M. stolouifer are common on many decaying sub- 

 stances. M. syzygites occurs on decaying toadstools and other large 

 fungi. Pilobolus crystallinus, Piptocephalis freseniana, and Chaeto- 

 cladium jonesii occur on animal excrement. Phycorayces iiilens 

 grows on oily or greasy substances, as old bones, oil-casks, etc. 



(i) Place several clean glass slides in contact with a culture of 

 Black Mould, as described in (g). By removing these at difEerent 

 times the various stages of growth of the mould may be easily 

 studied. 



(j) In the latter part of summer and in the autumn, examine the 

 dead flies which adhere to window-panes, door-casings, and especially 

 to wires and strings hanging from the ceiling. The whitish powder 

 around the fly will indicate the presence of the Fly-fungus. Mount 

 some of this white powder in water and examine under a high power. 

 Tear out small bits of the distended abdomen of the fly, and examine 

 for internal portions of the parasite. 



(A) For future study in the laboratory the aquatic zygophytea 

 should be preserved in botlies of water containing just enough alcohol, 

 glycerine, or carbolic acid to prevent their decay. One fourth or fifth 

 of the first and second, and enough of the last to give a decided 

 odor, will usually do well enough. 



