44 THE LARCH CANKER 



septate, and in this case the germ tube is developed rather 

 earlier than when the spore becomes segmented, and it 

 may appear as soon as twenty hours after the ejection of 

 the spore. This method of germination is less common 

 than the last, but very many cases were observed, and 

 the spores did not afterwards become septate. Either 

 one germ tube grows out terminally, or one from each end ; 

 in one case two germ tubes 'appeared at the same end 

 (fig. 20, C). 



The germ tubes vary in size (the larger ones are about 

 4 fj. broad), and may grow to a considerable length without 

 branching. One unbranched hypha attained a length of 

 140 /x in less than twenty -six hours. But generally the germ 

 tubes branch when they are much shorter than this and 

 form a fairly densely interwoven mass, even in tap -water 

 without any added nutriment. The walls of these hyphae 

 are thin and colourless. 



As the hyphae grow and use up the food at their dis- 

 posal, they frequently fuse with each other. These fusions 

 were observed by Willkomm, though his figures are mis- 

 leading as to their method of formation. I have noticed 

 three kinds of fusions. Firstly, when one hypha grows so 

 as to meet another broadside, the apical wall of the one 

 may be digested, and at the same time a hole be formed 

 in the side of the other. In this case the former hypha does 

 not continue its growth. -Secondly, one hypha may grow 

 over another and lie across it ; a clamp connexion may then 

 be made, in the form of a branch, which grows out from one 

 hypha and fuses with the other. I have not observed from 

 which hypha this branch usually arises. It does not generally 

 connect points which have been in contact, but is usually 

 bent, and connects the side of the upper hypha with the 

 top of the lower hypha. Thirdly, two hyphae growing 

 parallel with each other 5-20 /x apart may each send out 

 a branch hypha, and these two branches fuse by their 

 apices. Possibly their meeting in this way is merely acci- 

 dental, though the large number of fusions of this kind 

 suggests that some stimulus attracts the two growing apices 



