CHAP. I X MA A' A TTIA CE.-E—ISOE TA CE.E 



03 



The GametopJiyte 



The germination of the spores and development of the 

 prothallium were first investigated by Luerssen ^ and Jonkman ^ 

 in Angiopteris and Alarattia, d^nd later by the latter investigator 

 for Kaulfussia? 



The spores are of two kinds, bilateral and tetrahedral, but 

 the former arc more common. They contain no chlorophyll, 

 but oil is present in drops of varying size, as well as other 

 granular bodies. The nucleus occupies the centre of the spore 

 and is connected with the wall by fine protoplasmic filaments. 

 The wall of the spore is colourless and shows three coats, of 

 which the outer one (perinium) is covered with fine tubercles. 



Germination begins within a few days and is first indicated 

 by the development of chlorophyll. This does not, as Jonk- 

 man * asserts, first appear in amorphous masses, but very small, 

 faintly-tinted chromatophores appear between the large oil- 

 drops, and these rapidly increase in size and depth of colour 

 as germination proceeds, and their number increases by the 

 ordinary division. In the bilateral spores the exospore is 

 burst open above the thickened ventral ridge found in these 

 spores, and the growing endospore slowly protrudes through 

 this. The spore enlarges to several times its original diameter 

 before the first division occurs, and forms a globular cell in 

 which the large chloroplasts are arranged peripherally. 



The first division takes place about a month after the spores 

 are sown, and is perpendicular to the longer axis of the cell, 

 dividing it either into two equal parts, or the lower may be 

 much smaller and develop into a root-hair. In the former case 

 each cell next divides by walls at right angles to the first, and 

 the resulting cells are arranged like the quadrants of a circle, and 

 one of these cells becomes the two-sided apical cell from which 

 the young prothallium for a long time grows (Fig. 130), much 

 as in Aneiira. This type of prothallium, according to Jonkman,^ 

 is commoner in Marattia than in Angiopteris, where more 

 commonly a cell mass is the first result of germination. This 

 latter is usually derived from the form where a root-hair is 

 developed at first. In this case only the larger of the primary 



1 Luerssen (5). ^ Jonkman (i). ^ Jonkman (2). 



■* Jonkman, Bot. Zcit. 1S7S, p. 136. ^ Jonkman, I.e. p. 146. 



