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1901] CURRENT LITERATURE 139 
meaning a matter of inference rather than statement. While the well- 
informed English reader finally comes at his meaning, the paper must be 
baffling to the foreigner who is compelled to translate——J. M 
PROFESSOR HARPER has given us a detailed description of the sexual 
reproduction of Pyronema.” The account is of especial interest, for it pre- 
sents another instance of the fusion of multinucleate gametes, and is an impor- 
tant corroboration of Stevens’ studies on A/bugo bliti with respect to the 
behavior of cytoplasm and nuclei under such conditions. 
The oogonium of Pyronema, as is well known, puts forth a conjugation 
tube (trichogyne) whose tip fuses with the antheridium. e tube is sepa- 
rated from the oogonium by a cross wall before its fusion, and this septum is 
later absorbed, when the protoplasm from the antheridium passes into oogo- 
nium and fertilizes the shee Mcheiiaie 
The oogonium and a Itinucleate f the start. The con- 
jugation tube likewise contains many nuclei, but these break down before 
fertilization. The number of nuclei in the oogonium is variable but there 
may be an many as two hundred. These gather in the central] region of the 
Structure, forming a closely packed collection at the time of fertilization. 
A great many sperm nuclei enter the oogonium through the conjugation tube, 
but they are hardly likely to equal the female nuclei in number. e sperm 
nuclei are attracted to the central mass of female nuclei, and shortly after- 
wards are found fusing in pairs with these elements. ome nuclei are 
always left over unmated, and these may be recognized for a long time by 
their smaller size. There is evidence that they finally break down. 
The ascogenous hyphae spring directly from the fertilized oogonium, and 
as they develop the oogonium becomes rapidly emptied of its protoplasm 
and is finally left as a hollow cyst. The development of the asci is not essen- 
tially different from Peziza, Ascobolus, Erysiphe, and other types. The 
young ascus is the second cell of a curved branch. It contains two nuclei 
that fuse, and these are not sister nuclei. The fusion nucleus gives rise by 
successive mitoses to eight nuclei accompanied by the beautiful asters that 
Harper has described for several other forms, and the ascospores are cut out 
of the cytoplasm by these asters in the characteristic manner. 
The ascocarp of Pyronema is a compound structure involving several sys- 
tems of ascogenous hyphae from as many fertilized oogonia. The elements 
become so mixed that it is impossible to separate them. However, the — 
§enous hyphae may be readily distinguished from the vegetative mycelium 
that forms the envelop of the ascocarp and the paraphyses in the hymenium. 
Harper points out that the characters most distinctive of the ascogenous 
hyphae are large nuclei, many times larger than those of the vegetative 
mycelium. 
‘7 HARPER, R. A.: Sexual reproduction in hatin confluens and the caashaiver 
of the cman Ann. of Bot. 14: 321. pls. 7 1900, 

