COLLECl^ING AND PRESERVING MATERIAL. 289 



species. Since the plants may be grown promptly, the material 

 used should be living. 



UicroBphsera or TTncinula or Erysiphe. — Any species of mildew 

 will answer. Microsphcsra grows everywhere on the leaves of 

 the cultivated lilac. Erysiphe is abundant on the leaves of blue 

 or white vervain ( Verbena hastata and V. urticafolia) and many 

 Composite. Uncinula attacks leaves of many willows. About 

 midsummer, when the fungus has a white powdery aspect, gather 

 leaves and dry them under light pressure. Later, gather leaves 

 of the same species showing yellow and black dots (the fruits) on 

 the mycelium. Preserve in the same way. 



CyBtopns portulacse. — This species is abundant throughout the 

 summer on leaves and stems of purslane (Portulaca oieraced) 

 which grows in every garden and cornfield. Another species 

 grows in late spring on shepherd's-purse (Capsella bursa-pastoris) 

 and another on the pigweeds (Amaranthus sp.). Any one will 

 answer. The species on Capsella {Cystopus candidus) only oc- 

 casionally forms resting spores in that host. They may be found 

 in abundance in the flowers of radish which become much enlarged 

 and distorted when this fungus is parasitic thereon. All species 

 may be known by the white blisters formed by lifting the skin of 

 the host. Preserve in formalin or alcohol leaves and stems of 

 host bearing blisters. Some may also be dried. 



Lichens. — Any common foliose species which forms apothecia 

 abundantly will answer. A bright gray species with black apo- 

 thecia {Pkyscia stellarii) is abundant on tree trunks, as is also a 

 yellowish species with orange apothecia (Theloschistes polycarpd). 

 These may be collected at any convenient time, and kept dry. 

 Besides these, collect other foliose forms; also species of Cladonia 

 growing on the ground, with body much lobed and the apothecia 

 coral-red knobs on upright gray stalks; also species of Usnea, 

 clothing the branches of trees with gray-green shrub-like or hair- 

 like tufts. 



Hushroom. — Any species with cap and gills will answer. They 

 may be found in woods throughout the summer and especially 

 in late summer or autumn during a rainy season following 

 drought. Only the fructification need be collected. Select a 

 small firm species with well defined stalk, cap and gills. Col- 

 lect fructifications in all stages of development from young to 

 mature. Preserve as soon as gathered in formalin or 70 per cent, 

 alcohol. 



