台灣水?的抱子生成及配子生成

Abstract

l. 孢子囊及蓋膜同來自葉舌下一群上皮細胞，此群上皮細胞上半部產生為蓋膜，而下半部則生成孢子囊。但兩者早期發育並無明顯界限。 2. 小孢子囊和大孢子囊早期發育無法由形態區分，其細胞大小均勻，原生質內含物相似，細胞排列亦不規則，沒有解剖上特徵顯出孢子囊組織內細胞，那些發育為 Trabecula 或成為孢子母細胞。 3. 小孢子母細胞分化（即細胞增大）之前，小孢子囊內組織分化為孕性細胞區（深染色區）和不孕性細胞區（淺染色區）。孕性細胞區之細胞經增大和分裂為四分孢子(tetrads)，由此發育成為 tetragonal type 排列的小孢子。大孢子母細胞之分化（即細胞增至比鄰近細胞約四至五倍）在孢子囊內之一切其他細胞進行任何形態上之變化之前。之後，大孢子母細胞亦行分裂經四分孢子而最後成為 tetrahedralt type的大孢子，而其餘的大孢子囊組織則發育為營養層及 trabeculla。 4. 另外，有些大孢子囊內有些細胞增大到幾乎是成熟大孢子母細胞大小，但最後並不產生大孢子，而分裂成更小細胞，其最後可能成為營養層的一部分，或者可能走另一分化方向變成小孢子母細胞，而造成混生型孢子囊。 5．一生長季最先形成葉子為大孢子葉，接著為小孢子葉，但在消長次序中其經常不太規則。 6．小孢子發芽後產生一原葉細胞及一藏精器，藏精器由外圍有四個細胞（即保護層）及內有四個細胞所組成。其內四個細胞最後各發育成為一個多鞭毛的精細胞。 7．成熟大孢子具有一大且橢圓形的核位於基部，其可經多次核分裂，產生許多核後，才行細胞壁形成。細胞壁形成方向是先由頂部開始，再由周圍向中心而在孢子壁逐漸形成一多細胞組織，此即為雌性配子體。第一個藏卵器形成。來自這些最先形成的細胞之一，常位於配子體頂部中央位置。藏卵器數目似乎不一定，若無授精作用產生，則可不斷有新的藏卵器生成，直到貯在孢子內養分消耗完為止。假根生成是來自孢子壁裂開後，部分露出外面的配子體頂部的外層細胞。這些假根可達2mm或更長。是否配子體所有露出部分的上皮細胞潛能上為藏卵器或假根的始源細胞，則尚未能確定。

1. The sporangium and velum have their common origin from a group of superficial cells located below the developing ligule. The upper part of these superficial cells give ride to the velum, and the lower part give rise to the sporangium proper respectively. No obvious boundary between velum and sporangium proper in the early stage of development. 2. The microsporangia and megasporangia are indistinguishable in their early stages of development. The size and cytoplasmic contents of sporogenous cells are homogenous, and the arrangement of cells is irregular. There is no way to distinguish the trabecula initial from the spore mother cells in the sporogenous tissue simply based on their anatomical feature. 3. Before the microsporocytes become apparent, the sporogenous tissue develops into fertile region (deeply stained region) and sterile region (lightly stained region). The cells is fertile region become slightly enlarged and undergo cell division, ultimately form tetragonal microspores. 4. Still in somemegasporangium primordium, some enlarged potential megasporocytes fail to give to the megaspdres. They undergo several repeated cell divisions. Probably some of them become microsporocytes, and still some others tapetal cells consequently these sporangia contain both megaspores and microspores-mixed type. 5. The megasporophylls always appear before the microsporophylls in a given growing season. Occasionally, this subsequent order is not apparent. 6. Following the germination of the microspore, it forms cell and four central cells. Each of the central cell gives rise to a single multiflagellate sperm cell. 7. The megaspore contains a large elliptical nucleus which is located at the distal part of the spore. It undergoes repeate unclear fissions to form a free nuclear structure. The process of wall-formation begins at the apex and proceeding centripetally. Finally the whole structure becomes a cellular megagametophyte. The first archegonium arises from one of the early formed cells at the center of the apical region. The number of archegonia formed in each gametophyte, When fertilization is delayed, seems to be indefinite. The archegonia form one after another till the supply of food in the spore becomes exhaused. Rhizoids have their origin in the superficial cells of the apical region on the exposed surface after the spore wall breaks. The rhizoid is of two millimeter or more in length.