'J2 Fortpflanzung. 



Fortpflanzung. 



164) Fräser, H. C. I., The development of the ascocarp in Lachnea 

 cretea. In: Annais of Botany, Bd. 27, S. 553—563, PL 42—43, 1913. 



Lachnea cretea Phil, is a small Discoin3'cete (Fungi) which occurs on plaster 

 ceilings. It was propagated on culture media and a large supply obtained. The 

 cytological study of various Ascomycetes has led to different views regarding 

 the behaviour of the nuclei and chromosomes in relation to the life cycle. One 

 school holds that two sexual fusions occur, (1) in the ascogonium, (2) in the 

 ascus, followed by two reduction divisions, the third division in the ascus being 

 known as brachymeiotic. The other school holds that the nuclei merely form 

 pairs in the ascogonium, without fusion, and undergo conjugate divisions until 

 the asci are formed when a sexual fusion occurs in each ascus. This school be- 

 lieves that the third mitosis in the ascus is an ordiuary division. Fräser resta- 

 tes her adherence to the former view, though the investigation in hand did not 

 furnish additional crucial evidence on this subject. The results obtained related 

 chiefly to the development of the archicarp, which arises in Lachnea cretea as a 

 coiled branch from one of the hyphae. A surroimding sheath is formed by neigh- 

 bouring hyphae. The archicarp differentiates into (l) the multicellular stalk, 

 (2) the coiled, multicellular ascogonium, and (3) the septate trichogyne. The 

 latter elongates and finally branches — a peculiarity not previously observed in 

 this group. The transverse septa of the trichogyne break down, and the pores 

 so formed became closed by a structure resembling in appearance the callus-pad 

 of a sieve-tube. The trichogyne has probably only recently ceased to function. 

 The ascogonium contains numerous small nuclei. There are very large pores bet- 

 ween the cells, so that the nuclei pass freely from cell to cell and no doubt fuse 

 in pairs at this time. Ascogenous hyphae then arise from the various cells of the 

 ascogonium, and these form the asci in the usual way. Gates (London). 



165) Black, Caroline A., The morphology of lUccia frostii Aust. In: 

 Annais of Botany, Bd. 27, S. 511— 532, PI. 37—38, 1913. 



Biccia is one of the simplest of the Liverworts, the thallus being a circular 

 rosette attached to moist ground. The plants are dioecious, the antheridia and 

 archegonia being borne on separate individuals. The air-chambers in the thallus 

 originate by the upward growth of adjacent filaments around a depression, as 

 described by Leitgeb. The development of the sex organs and the spores is 

 described. No centrosomes or centrospheres were found in the spore mother-cells. 

 The sporophyte number of chromosomes is 16 and the gametophyte number 8. 

 The nucleus of the mature spore in very small, and is surrounded by oily food 

 material. 



In spermatogenesis, in the last division the spindle is placed diagonally in 

 the cell, but no cell wall is formed. Small granules corresponding to centrosomes 

 are sometimes found at the poles. In the diagonal or sperm cells the blepharo- 

 plast first appears as a sharply differentiated pari of the cytoplasm in an angle 

 of the cell. There was no evidence that this blepharoplast originated from the 

 polar granule of the previous mitosis. As the sperm cell developes into the 

 sperm the blepharoplast elongates as a cord, the nucleus becoming crescent-shaped 

 and homogeneous. The blepharoplast then becomes closely applied to the nucleus, 

 continuing as a narrow thread which terminates in a thickened head, and from 

 the latter two cilia are produced. When mature, the sperm consists of a homo- 



