GERMINATION AND GROWTH. 



145 



production of cylindrical tubes, which start from the upper 

 extremity of the wedge-shaped spores, or more rarely from the 

 base. These tubes are straight or twisted, simple or bifurcated, 

 and each of them very soon emits four monosporous spicules, at 

 the same time that they become septate. The sporules are in 

 this instance globose. 



In Uromyees germination follows precisely 

 the same type as that of the upper cell of 

 Puccinia ; in fact, Tulasne states that it is 

 very difficult to say in what they differ from 

 the Puccinia which are accidentally unilo- 

 cular. 



In Oystopus a more complex method pre- 

 vails, which will be examined more closely 

 hereafter. 



In Puccinia, as already observed when 

 describing their structure, the pseudospores 

 are two-celled. From the pores of each cell, 

 which are near the central septum, springs 

 a clavate tube, which attains two or three 

 times the total length of the fruit, and of 

 which the very obtuse extremity curves 

 more or less in the manner of a crozier.* 

 This tube, making a perfectly uncoloured 

 transparent membrane, is filled with a 

 granular and very pale plastic matter at ««>«"«"«""»• (Tulasne.) 

 the expense of the generative cell, which is 



soon rendered vacant ; then it gives rise to four spicules, usually 

 on the same side, and at the summit of these produces a reni- 

 form cellule. The four sporules so engendered exhaust all the 

 protoplasm at first contained in the generative cell, so that their 

 united capacity proves to be evidently much insufficient to con- 

 tain it, the more so as it leads to the belief that this matter 

 undergoes as it condenses an elaboration which diminishes its 

 size. In all cases the spicule originates before the sporule which 

 it carries, and also attains its full length when the sporule ap- 

 * Tulasne, in his "Memoirs on the Uredines." 



