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break the leaf epidermis and be scattered upon new leaves to 

 start an epidemic which, by midsummer, will have caused all 

 the basal leaves of the hollyhocks to wither. This cosmopolitan 

 has apparently colonized the world within the last century. 

 Within the concise records of botanical journals, recording the 

 occurrence of rust on plants of the mallow tribe, is hidden many 

 a story of stow-away travel. (26) The earliest record proves it 

 was growing in Chili in 1852. In 1857 it was reported on holly- 

 hocks in Australia. The first record for Europe reports it in 

 Spain in 1869. In 1873 it is reported from Bordeaux and Devon- 

 shire. By 1890 it had apparently colonized Europe and there is 

 mention of it in Asia, Africa and the Canary Islands. In North 

 American records the earliest date of its occurrence is 1888. (30) 

 It evidently travelled westward. In 1905 it had not been found 

 in Minnesota (33) but today it is found all over the United 

 States. Many a gardener has come to accept yellowed leaves 

 on the blossoming hollyhock spikes; the energetic gardener 

 will need to give a weekly dusting of sulphur to his new plants 

 if he will keep out the rust. (36) Even should this be effected 

 at Wheaton we shall keep the rust in our community as the 

 little round-leaved mallow, a weed of the campus green, is also 

 host to the rust. 



One needs microscopic mounts of cut leaves in order to see 

 more of a rust plant than its fruit. The delicate, colorless strands 

 of the fungus push their way between the cells of a leaf with a 

 minimum of disturbance. They send only capillary branches 

 through the cell walls and then, in contact with the living host 

 cell, enlarge into swollen tips for feeding. These short branches, 

 within the cell wall, but within the protoplasm only in the sense 

 in which an ingested food particle is within an amoeba, are 

 called haustoria. (49) By means of these the rust invader feeds 

 without killing the host cells. The invaded cell is host perforce 

 but the rust parasite feeds and drinks with a restraint which 

 preserves the source of supply until, as the demands of fruiting 

 time overcome the habits of restraint in the rust, water and sug- 

 ar become scarce for two. Even then the drain upon the host is 

 evident chiefly in the gradual drying out of the infected areas. 

 It follows naturally upon these feeding habits of the rust para- 

 site that a healthy plant is preferred as host: a reversal of the 

 old dictum that the weakling is the natural prey to disease. (48) 



