BY JOHN SHIRLEY, D.SC. 65 



recall in appearance those of the rhizinae. At an early stage 

 the original coil is lost sight O'f under the outer layer of 

 numerous brown threads, but a section which cuts these 

 away renders the now enlarged coil visible. (Plate VI., 

 fig. 10.) 



As soon a® the wall of the spermagonium has grown 

 into touch with the upper cortex, the portion of the sper- 

 magonial wall in contact becomes raised into a papilla, 

 which breaks through the cortex (Plate VII., fig. 11), and 

 then opens to form a pore for the discharge of the sper- 

 matia. The lip O'f the ostiole is the thickest portion of the 

 wall. In a few instances the upper cortex was observed 

 to increase in thickness by downward growth towards the 

 spermagonium, the two dark-brown mass s of hyphse inter- 

 wove, and a pore developed by separation of the hyphse 

 in the cortical filaments that now form part of the sper- 

 magonium. The centre of the ostiole is depressed, with 

 raised circular lips. The opening may appear on the sur- 

 face of the thallus as a black or brown speck, or may be 

 concolorous with the upper cortex. 



Thei jointed sterigmata, the stalks that bear the 

 spermatia, the supposed male germ-cells, radiate from all 

 parts of the inner wall towards the centre. In Parmelias 

 they are .02-. 04 x .002-. 0008 mm. in cross diameters, and 

 usually composed of 5-7 jointed cylindrical cellules. By 

 some authors these jointed sterigmata are called arthro- 

 sterigmata, but 1 y others this term is restricted to those 

 spermatial supports thati have cellules broader than they 

 are long. 



The study of the sterigmata is difficult from the fact 

 that they are bound together by a gelatinous substance; 

 which, in sections of spermagonia parallel to the sterig- 

 mata, cause the section to appear as if homogeneous. This 

 appearance is further aided by the colourless or faintly 

 yellow colour of the threads. 



Tbe spermatia of Parmelias are of two types, the 

 first series possess acicular spermatia with slightly fusiform 

 apices, as in P. perJata, P. perforata, and tlieir allies. 

 This form of spermatium is also characteristic of the genera 

 Sticta and Stictina. Tlie second section have acicular- 

 cylindrical spermatia, as in P . laceratula, P. polytropa, P. 

 placorhodioides and other Australian species. In this re- 

 spoct they resemble the genus Physcia. 



The spermatia in the genus Parmelia are .005-. 008 x 

 .006-. 001 mm. in diameter, and are colourless and do not 

 stain readily. They are found either m situ on the sterig- 



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