REED: SPECIALIZATION OF PARASITIC FUNGI 387 



Steiner (150) found that the mildew on Alchemilla was confined 

 to the species of this genus. He also claimed to be able to distinguish 

 specialized races within this genus of host plants. He found that 

 conidia from Alchemilla pastoralis and A. flexicaulis were alike in 

 infecting power except that conidia from the former host would not 

 infect A. Alpigena and only slightly A. pubescens, while conidia from 

 A. flexicaulis infected A. Alpigena slightly and A. pubescens not at all. 

 Conidia from A. impexa would not infect A. Alpina vera nor A. nitida, 

 while conidia from A. pastoralis at least partially infected these hosts. 

 Steiner also found that conidia from the Vulgares section of the host 

 genus would not produce full infection on species of the Alpinae sec- 

 tion, although conidia from species of the latter section vigorously 

 infected species of the former. Steiner noted marked differences in 

 the relation of the species of Alchemilla to the mildew, dividing them 

 into the following groups: (i) Susceptible species, as A. impexa; 

 (2) immune species, as A. conjuncta; (3) species susceptible to the 

 mildew from some hosts, while immune to that from others, as A. 

 micans. 



Sphaerotheca Humuli (DC.) Burr. var. fuliginea (Schlecht) Sal- 

 mon. Salmon (128) has made a few tests with conidia of this mildew 

 from Plantago lanceolata and Taraxacum officinale. Conidia from the 

 former infected the same host but not Plantago major nor Taraxacum 

 officinale; conidia from Taraxacum officinale infected T. officinale but 

 not Fragaria (cult, sp.), Plantago media nor P. lanceolata. 



Oidium on Euonymus japonicus. Salmon (131) reports the fol- 

 lowing results with this mildew whose identity was not fully deter- 

 mined; conidia from Euonymus japonicus infected E. japonicus var. 

 aureus, var. albomarginatus, var. ovatus aureus, var. microphyllus, var. 

 President Gunter, E. radicans var. microphyllus and var. Silver Gem, 

 but not E. nanus, E. americanus var. angustifolius, E. chinensis, E. 

 europaeus, E. radicans var. carrierei, Celastrus scandens, C. articulatus, 

 C. orixa nor Prunus laurocerasus var. latifolia. 



Additional Fungi 



Physiological specialization has also been investigated in a few 

 other groups of fungi by a number of different workers, but, outside 

 of the rusts and powdery mildews, no extensive studies have been 

 made. 



Synchytrium taraxaci de B. and Wor. In the Chytridiaceae, 

 Liidi (95) has tested the infecting capacity of swarmspores of Syn- 

 chytrium taraxaci from Taraxacum officinale. He tried to infect nine- 

 teen species of Compositae which do not belong to the subdivision 

 Cichoraceae, but with negative results in every case. He also used 



