io6 



FfRST GROUP. THALLOPHYTES. 



spots on the lowest turn of the archicarp, and grow up outside the screw ; one of them 

 grows faster than the other, reaches the uppermost turn, and applies its apex closely to 

 it (B). This branch is the antheridial branch, and conjugation takes place between its 

 apex and the apex of the archicarp, the cell-wall becoming dissolved at the point of 

 contact and the protoplasmic contents of the two cells coalescing. Soon after this new 

 filaments shoot out from the lower part of the antheridial branch and of the archicarp; 

 these increase in number, attach themselves closely to the screw (C), and ultimately 

 completely invest it. Then a layer of polygonal cells is formed out of these filaments 

 by means of transverse divisions, and this layer forms the envelope of the archicarp. 

 Next the cells of the layer grow out on its inner side and the papillae thus formed are 

 divided off by transverse septa (E) t and while the envelope increases in size the space 



FIG. 66. Development of Eitrotium repcns. A small part of a mycelium with the gonidiophore c and young 

 archicarps as. B the spiral archicarp as with the antheridial branch /. C the same with the filaments beginning to 

 grow round it to form the wall of the perithecium. D a perithecium seen from without. E, F young perithecia in 

 optical longitudinal section; tu parietal cells, ./"the filling tissue (pseudo-parenchyma), as the archicarp. G an ascus. 

 H an ascospore. After de Bary. A magn. 190, the rest 600 times. 



which it encloses is also enlarged and is filled up with the papillae, which are closely 

 packed and grow up to the archicarp and between the turns of the screw which are now 

 further apart ; then this new growth of filaments divides by the formation of transverse 

 septa into a number of cells of equal diameter, and finally the space between the 

 envelope and the turns of the screw is filled with a pseudo-parenchyma, the filling- 

 tissue. During these proceedings numerous transverse walls are formed in the archi- 

 carp, and a number of branches are put out from its cells, which grow in every direction 

 between the cells of the filling-tissue, form septa and ramify ; their ultimate ramifi- 

 cations are the asci (G), which consequently owe their origin to the ascogone fertilised 

 by the antheridial branch. These interior changes are accompanied by a considerable 



