中文摘要：

为了阐明雌雄异体紫菜减数分裂的发生时期，对坛紫菜生活史的各阶段进行了细胞学研究。用卡诺固定液（无水酒精：冰醋酸=3：1）分别固定室内培养的坛紫菜各生活阶段的活体材料，在明亮处放置数日使细胞褪色至白色。然后，先用铁矾苏木精染液对固定材料进行染色处理，再进行压片、显微观察和拍照记录。观察结果表明，精子囊细胞、叶状体营养细胞和2个细胞的壳孢子萌发体中的核相是单倍的，染色体数N=5；果孢子、丝状体细胞、膨大细胞和壳孢子的核相是双倍的，染色体数2N=10。精子囊细胞、果孢子和丝状体细胞的分裂是有丝分裂。在壳孢子萌发的第1次细胞分裂过程中，观察到了减数分裂的细线期、偶线期、双线期、终变期、中期和后期等；壳孢子萌发的第1次细胞其分裂结果导致了染色体数目减半。上述研究结果表明，在雌雄异体的坛紫菜生活史中，壳孢子萌发的初始分裂是减数分裂。

英文摘要：

In the present study, a chromosomal observation on the heteromorphic marine red alga Porphyra haitanensis Chang et Zheng was conducted, mainly to ascertain where the meiosis occurs in the life history of the dioecious Porphyra. The living materials of different life phases in P. haitanensis were fixed in Camnoy＇s fixative fluid, and stored at the light conditions to leach phycobilin pigments. The samples were then stained with Wittmann＇s aceto-iron haematoxylinchloral hydrate and examined under a photomicroscope （Olympus BH） with oil immersion lens. Chromosome counts indicated that spermatia, vegetative cells gametophytic blade and conchospore germlings are haploid （n=5）; whereas carpospores, conchocelis, conchosporangial cells and conchospores are diploid （2n=10）. The cell divisions that occurred in spermatia, carpospores and conchocelis are mitosis. Leptonema, diplonema, diakinesis, metaphase and anaphase of the meiosis and the change in ploidy at the two-celled stage were observed in conchospore germlings. Characteristics of the first division of conchospore and the change in ploidy at the two-celled stage indicate that meiosis occurs during the germination division of conchospore in Porphyra haitanensis.