HEART-HOT 



97 



preparations for making observations on these patches were 

 obtained by first soaking sections in dilute HC1 until 

 bleached, then staining with safranin and mounting in 

 Canada balsam. The 

 hyphal walls, which were 

 previously dark brown, 

 readily absorb the saf- 

 ranin, whilst those which 

 were formerly colourless 

 remain so. In sections 

 mounted in this way the 

 following details may be 

 observed. 



As shown in fig. 35, the 

 hyphae at the edge of 

 the dark patch are easily 

 distinguishable, though 

 frequently two or three 

 may be seen growing side 

 by side in fascicles and 

 touching for their whole 

 length. They grow in 

 this way up and down 

 the tracheides and along 

 the* medullary rays. 

 Nearer the middle of the 

 black patch the hyphae 

 are very irregular, with 

 swellings here and there ; 

 and where two hyphae 

 are touching, the inter- 

 mediate walls have often 

 been partially or wholly 

 digested, so that several adjoining hyphae come to have 

 the appearance of one very large hypha (fig. 35, h). 



In the centre of the patch still further disorganization is 

 found. The walls of some hyphae break down entirely, 

 setting free a jet black liquid which stains all the contents 



n 



FIG. 35. Longitudinal section near 

 the edge of a black speck, after bleach- 

 ing in dilute hydrochloric acid : b, bore- 

 hole ; h, two hyphae joined by the disso- 

 lution of their adjoining walls ( x 800). 



1888 



