OF ARTS AND SCIENCES. 43 



the cortical cells, as well as those immediately beneath them, are seen 

 to be colored brownish. Tliese initial appearances would mean but 

 little did they not later become more emphasized, and more evidently 

 associated with apothecial development. Tlie tip swells more notice- 

 ably, owing to the active branching and interweaving of the hvphaj, 

 and becomes club-shaped or even subspherical in section, the cortex 

 becomes in many cases dark brown in color, and the delicate branches 

 composing the upper part of the complex mass of hyphai which causes 

 the swelling of the tip, exhibit at the central point a slight tendency 

 toward a regular arrangement perpendicular to the surface. As yet 

 there has appeared no definite hyphai coil in any part of the tissue 

 under examination, nor have I been able to discover, either in the 

 tissue or on the surface, any appearance of a trichogyne. The ten- 

 dency toward a regular arrangement in the upper part of the primor- 

 dial mass of hyphaj soon becomes more marked, and there now exists, 

 just below the surface, a layer of short parallel threads, the young 

 hymenium, springing from the dense tissue of the primordium, and 

 still in genetic connection with the tissue above. The tip in section, 

 owing to the expansion in area of the young hymenium, becomes less 

 spherical and flatter, and the brown coloration, considerably less 

 marked than before, is now limited to the cortex immediately above the 

 young hymenium. The paraphyses attain a length of 25 /x to 30 /x, and 

 then their rate of growth becomes much less rapid. The same partial 

 cessation of growth does not however take place in the surrounding 

 and overlying tissue, and the latter, forced upwards, becomes torn away 

 from the paraphyses and forms above the disk an arched cavity. 



At this, or at a slightly earlier stage, there are to be seen in the hy- 

 pothecium certain cells, the origin and object of which I am at a loss 

 at present to exjjlain. They are differentiated from the surrounding 

 cells by their greater size, more rounded shape, and oily or granular 

 contents. Their arrangement, furthermore, seldom exhibits any degree 

 of regularity. The tissue overlying the disk gradually begins to show 

 signs of approaching dissolution. The brown color of the rind spreads 

 to the tissue beneath, and the whole mass covering the young hyme- 

 nium becomes yellow or brown. The later development is quite nor- 

 mal. The expansion of the disk ruptures the rind in a stellate manner, 

 and as soon as it appears upon the surface the hymenium increases 

 with such rapidity that the thallus is bent back upon itself. 



The formation of an exciple is extremely simple. As soon as the cor- 

 tex is ruptured, the paraphyses again increase rapidly in length, until 

 their tips are level with the surface, and the cortex, instead of being 



