THE GAMETOPHYTE 119 



I. THE GAMETOPHYTE. 



The first account of the germination and development of the gametophyte 

 in the Marattiaceae was pubHshed by Luerssen (Luerssen 2), who studied the 

 germination in Marattia cicutcsfolia and in Angiopteris. Not long afterward the 

 Dutch botanist, Jonkmann, pubhshed an account of the development of the prothal- 

 lium in both Marattia and Angiopteris. His original paper (published in Dutch, 

 but afterward translated into French) gives an extremely satisfactory account of the 

 germination and development of the prothallium and reproductive organs (Jonk- 

 mann 1). Somewhat later he also published a preliminary account of the germina- 

 tion in Kaulfussia, but apparently the work was never published in full (Jonkmann 

 2). In 1892 Farmer (Farmer 1) described the gametophyte and embryo in Angi- 

 opteris evecta and in 1894 the writer (Campbell 3) gave an account of the prothallium 

 and embryo in Marattia douglasii collected in Hawaii. Two years later Brebner 

 (Brebner 2) described the prothallium and embryo in Dancea simplicifolia. In 

 1908 the writer published an account of the prothallium and young sporophyte of 

 Kaulfussia (Campbell 9) and in 1909 a preliminary note was pubhshed in regard 

 to Dancea (Campbell, 10). 



The following account of the germination is based mainly upon the work of 

 Jonkmann. I have, however, examined the early germination stages in Marattia 

 douglasii for comparison with Jonkmann's account, and, so far as my experiments 

 went, it agrees entirely with the species described by Jonkmann. 



The ripe spores of the Marattiaceae are small and may be either of the bilateral 

 type or tetrahedral (radial). According to Jonkmann, the bilateral spores are much 

 more abundant in Marattia than the radial spores, but in Angiopteris the radial 

 spores predominate. The wall of the spore (see Jonkmann 1, pp. 203, 204) shows a 

 differentiation into an inner membrane or endospore and a middle layer, the exospore, 

 which is often found divided into layers. There is a very thin external coat, the 

 perispore or epispore, which is generally thrown off in the early stages of germination 

 or even before germination begins. All of the membranes except the epispore are 

 colorless, while the latter is a more or less pronounced yellowish brown tint. The 

 surface of the spore is roughened by small papillae which arise from the exospore. 

 The spores contain no chlorophyll, but there is a considerable amount of oil present, 

 which appears as drops of varying size, and there are also other granular contents — 

 starch and albuminous granules. The nucleus lies in the center of the spore and 

 is connected with the peripheral protoplasm by delicate protoplasmic filaments. 

 Germination begins quite promptly under favorable conditions and within about 

 a week the spores, which hitherto were quite colorless, begin to show a greenish 

 tint, due to the development of chlorophyll. Jonkmann states that the chlorophyll 

 appears first as flocculent masses near the nucleus, but these apparently amorphous 

 masses are really composed of very small, faintly tinted chromatophores, which lie 

 between the large oil drops and rapidly increase in size and depth of color as 

 germination proceeds, their number increasing by the usual division. The chloro- 

 plasts later become very conspicuous and are distributed in the periphery of the now 

 very much enlarged spore, the outer membranes of which are ruptured so as to 

 expose the endospore, containing the nucleus and numerous large and conspicuous 

 chloroplasts. Starch granules are also to be seen in most cases. 



The cell remains undivided until it has attained a size many times greater than 

 that of the spore. The first division wall, which is formed about a month after the 

 spores are sown, is transverse both in Angiopteris and Marattia, and, like that in 

 the germinating spore of Ophioglossum, divides the primary cell into two nearly 



