79 



They are of a smoky or slightly greenish colour, and present a raised! 

 scar at each end at the places where they were formerly articulated 

 together. 



It remains uncertain on what part of the leaves these tested spores- 

 grew, but there can be very little doubt that it was at the margins of 

 erosions. Nothing was seen that contradicted this. The spores were- 

 seen only in slide preparations of the spots from the leaves. The 

 spores were the main feature of the preparations as they came 

 originally to the microscope. 



The spores of this Oospora-like fungus on germinating become in. 

 many instances two-celled. Sometimes they are 

 two-celled on removal, but this is exceptional. 

 On being cultivated in water-infusion of passion- 

 vine leaves a large proportion of the spores 

 become two-celled, and in this condition still 

 possess many of the features of the spores as 

 they fall from the aerial chains in which they 

 grow. On becoming two-celled the spores send 

 out from either end, and sometimes also from 

 the sides, of the component cells, colourless 

 mycelium composed of cells, having somewhat 

 the form of the component cells of the spore. 

 In other words the septa of the mycelium are 

 separated from each other by a distance from 

 one and a half to two times as great as the width 

 of the mycelial thread itself. 



It appeared to me that the mycelium pro- 

 duced conidia, which were at first ellipsoidal, but 

 which, through a process of budding, decreased 

 in size, and became nearly spherical while continuing the process of 

 budding. In one case I saw growing side by side from the end of a. 

 spore four such ellipsoidal conidia. In other cases I saw the same 

 conidia growing from the side of well-developed mycelium that had 

 grown within twenty-four hours from one of the original spores. 

 (Pig. 90.) 



Comparisons. 



The edges of the holes in apricot and almond leaves are often 

 fringed in the manner described in the case of the corroding fungus of 

 the Passion-vine. A comparison of the spores in the two cases- 

 discloses no essential difference. They are borne in the same way > 

 and are of the same shape, colour, and size. 



Examination of the edge of an apricot shot-hole for all the kinds of 

 spores discoverable gave on one occasion the following results : 



1. The above-mentioned spores in proportion of ten to one of any* 



other kind. 



2. Quite a number of Alternaria spores. 



3. Few spores resembling those of Cladosporium, but possibly- 



belonging to Alternaria. 



4. One each of three other kinds of spores, manifestly erratic. 



X400 



Fig. 90. Germination in- 

 water of the spores of the- 

 Oospora-like fungus con-- 

 nected with the faulty 

 leaves of the passion-vine. 



