46 LINDSAY, ON ABROTHALLUS. 



seen^ especially under the use of iodine and other reagents, 

 to be distinct from the thecal wall,, more particularly at the 

 apex, where a considerable space sometimes intervenes be- 

 tween them. The protoplasm slowly acquires a pale yel- 

 lowish tint, and become smore granular ; bye and bye it 

 exhibits division into oval masses, which are the future 

 spores. Two button-like nuclei of a pale lemou-yeiloAv 

 coloxn* soon appear, and occiipy those parts of the spore which 

 are subsequently divided by a central septum into the 

 two loculi. Meanwhile the theca has increased in breadth 

 towards the apex, and has assumed more of an obovate 

 form ; the spore- sac and thecal wall have been distended by 

 the gradual development of the spores. At this stage the 

 theca is a very pretty object under the microscope. The 

 protoplasm, as yet faintly coloured and finely granidar, is 

 studded over with the button-like nuclei of the spores, which 

 are more prominent than their walls or septa. A similar ap- 

 pearance may be readily observed in the young thecaj of 

 Parmelia parietina and some other lichens. This button- 

 studded appearance, however, is much better marked in 

 A. oxysporus, in which the spores remain colourless or very 

 pale, and the lemon-coloured nuclei consequently very pro- 

 minent ; besides the spores of A. Smitkii do not always 

 possess or exhibit the nuclei in question. The septum of the 

 spores now becomes apparent ; their walls are better defined ; 

 their colour has passed through various shades of yellow and 

 green till it has become an olive-green; and the nuclei or 

 secondary cellules remain or disappear. The distension of 

 the theca progresses in proportion to the maturescence of the 

 spores, the inferior extremity or pedimcle tapering suddenly 

 or gradually from the upper, sometimes almost siDlierical, 

 portion. Finally, the spore-sac and theca are ruptured at 

 the apex, and, immediately after the emission of their con- 

 tents, disappear. The spores escape, and after they are free 

 they expand in dimensions, acquire more of a brown colour, 

 and have a better-defined wall and septiun ; the loculi are 

 separated by a distinct constriction, and they exhibit an 

 inequality of size, one being considerably broader than the 

 other. Tulasne speaks of the thecse in the genus Abrothallus 

 being clavate ; but this aj)pears to me to be true of them 

 only in their young state. I have repeatedly tested the 

 amyloid nature of the thecae by solutions of iodine, diluted 

 and strong, but with negative results. In one or two cases 

 only did I discover a faint bluish tint developed; in the 

 majority the iodine merely communicated its own tinge or 

 produced no effect. This residt accords essentially with the 



