28 PROCEEDINGS OP THE AMERICAN ACADEMY 



Stages in their growth may readily be followed in a series of sections 

 closing with the mature apothecium. 



Let us take one of the smallest of these masses. It measures 

 0.C5 mm. in diameter, and of course possesses no trace of asci or para- 

 physes. Potassic hydrate makes the mass perfectly transparent, but the 

 most careful search in many specimens fails to reveal anything like an 

 ascogonium, or any cells larger or in any respect different from the 

 vegetative hypha3 which gave rise to the mass. Furthermore, although 

 this is presumably the youngest visible stage of the apothecium, and 

 the disappearance of the trichogyne is always said to be the mark of a 

 comparatively advanced stage, no coiled hypha is seen, and no vestige 

 of a trichogyne tip is to be found projecting above the smooth, unbro- 

 ken surface of the cortex. Treatment with tincture of iodine, or with 

 a solution of iodine and potassic iodide, also fails to bring out any 

 bint of the existence of an ascogonic system. Very often in the ex- 

 ternal part of these masses are seen, when treated with iodine, irregu- 

 larly shaped bodies of a dark brown color which might easily be 

 mistaken for the large, deeply-stained cells of an ascogonic hypha. 

 Careful focusing, however, or if that fails, crushing of the section, 

 shows that they are nothing more than algse which have become sep- 

 arated from the gonidial layer, enclosed in the hyphse forming the 

 apothecial primordium, and much distorted by the pressure of these 

 hyphse. 



The next stage in the development shows that the primordium has 

 increased rapidly in size. It now measures from 0.18 to 0.2 mm. in 

 diameter ; but with the exception of this increased size, and a rather 

 decided flattening of its lower part, there is no marked change. The 

 mass is still capable of being resolved into a confused and tangled ag- 

 gregation of hyphoB, but they are beginning to show a tendency to 

 grow in a general direction more or less perpendicular to the sur- 

 face. Neither ascogonium nor trichogyne has as yet ap[)eared. One 

 thing, however, must be borne in mind. The hyplune composing the 

 primordium have by this time become, by mutual pressure, rather 

 smaller and considerably more distorted than the medullary hyj^ha', 

 and are therefore much dissimilar from them in appearance. If now 

 a piece of an ordinary medullary hypha by any chance overlies our 

 section in a definite position, or if, by focusing too deeply, we come 

 upon one of such parallel hyphae, it will present the appearance of a 

 large-celled hypha embedded in the primordium, and might easily be 

 mistaken for an ascogenous hypha. No mistake, however, can easily 

 be made with regard to the presence or absence of a trichogyne, and 



