MEMOIRE STTR LA TRIBTJ DES HTSTERINEES. 409 



their upper ends, and b?come detached, more or less, completely from one another, 

 being often entirely bent backwards or twisted in different directions. They arc 



so like paraphyscs that their true nature has often been mistaken I 



thought at first that these spores must, before their separation, be united by a mem- 

 brane, but, although I have used different microscopes, different magnifying powers, 

 different sorts of light, and different chemical tests, I have never succeeded in dis- 

 covering the slightest trace of an enveloping membrane. The Hysterinca;, there- 

 fore, have two very different sorts of asci, viz. dehiscent asci (those formed by long 

 spores which become detached from one another), and closed asci (those which con- 

 tain spores of different sorts within a closed membrane)." 



INow upon this we would remark that a consolidation of 8 filiform 

 spores without an enveloping membrane cannot with any accuracy- 

 be called an ascus ; if (as Mons. Duby is convinced) no membrane be 

 present, the fructification would be somewhat analogous to the 

 bunches of spores borne on the lips of the paraphyses of Patellaria, 

 and must, we think, be looked upon as basidiosporous or stylo- 

 sporous, and not as ascigerous. This would not interfere with 

 Mons. Duby's classification, but would only necessitate a change in 

 definitions. 



In the third section of his Memoir, which contains, as we have 

 said, a systematic exposition of genera and species, two substantial 

 new genera are proposed. There is a third, " Aporia" which, how- 

 ever, is only a refuge for some plants of uncertain affinity, and which 

 is designated by the author as " anomalum et ambiguum." Of the 

 two others Ostreichnion is founded upon Lophium iinguiculatum of 

 Wallroth, and will probably be adopted. The other, Mytilinidion, 

 represents Hysterium aggregatum of De Candolle, and differs some- 

 what from Ostreichnion in the shape of the perithecium, and mate- 

 rially so in the spores. 



The fourth and last section contains some useful observations on 

 the value of the stroma and of the form of the spores for purposes of 

 classification in the ITypoxylese generally. With most of these ob- 

 servations we entirely concur, but we entertain great doubt as to the 

 character of dehiscence ascribed by the author to the fruit of Sph. 

 acuminata, rubella, and disseminans. We have not had an opportu- 

 nity of examining the latter species, but with regard to the two 

 former we have never had any doubt as to the existence of an en- 

 veloping membrane, or true ascus, and if this be so, Mons. Duby's 

 principle of classification would not be applicable. 



