Lancaster. — The Fung/ of Neir Zenhnul K i>i i\h\ii'ic Ordiids. 187 



tropical Pacific. The species specially referred to in this paper are Denclro- 

 hiiun Cunninqhamii Lindl,, Earina mucronata Lindl.. and Earina suavenJens 

 Lindl. 



If transveise sections of the roots of Earina or Dendrobium be examined 

 with the microscope it will generally be found that some of the cortical 

 cells contain each a yellowish-brown mass. Sometimes these masses are 

 few in number and small in size, but often they are present in abundance 

 and are conspicuous objects in the section. They are most plentiful in the 

 outer layers of cortical cells, and are seldom found in close proximity to the 

 stele. Close examination of these masses shows that they vary greatly in 

 size, in shape, and in the materials composing them. In colour and dense- 

 ness, too, they show variation, so that no two are alike, even in the same 

 cross-section. It will be of assistance in description to refer all these masses 

 to one or another of three chief classes, into which they may be divided, the 

 first class containing masses which consist almost wholly of a more or less 

 dense coil of well-defined fungal hyphae ; the second comprising those which 

 are dense and yellowish in colour, and in which no traces of hyphae are 

 observable ; and a third class consisting of masses which are intermediate 

 in structure between those of the first two classes. The bodies belonging 

 to the last class are usually composed partly of numerous granular bodies 

 and partly of what are evidently degenerating fungal hyphae. 



In the bodies of the first type the hyphae are thin-walled, almost colour- 

 less, often swollen slightly in places, and are usually coiled up in a more or 

 less dense mass. They are septate, the division walls being sometimes 

 very numerous, and they often branch freely. A vacuolated appearance 

 is nearly always observable, and sometimes the hyphae are seen to have 

 collapsed in places. 



The masses of the second class, although varying greatly in shape, gene- 

 rally have their edges well defined. They are usually of a yellowish colour, 

 and the substance of the mass appears homogeneous, no signs of fungal 

 hyphae being observable. Each of these masses is usually connected with 

 the walls of the cell in which it occurs by one or more narrow strands, Avhich 

 often appear to consist of protoplasm, but which are sometimes fungal 

 hyphae in a state of degeneracy. Sometimes the strands belonging to the 

 masses in adjacent cells appear to be continuous through the dividing cell- 

 walls, so that the strands would seem to connect the yellowish bodies with 

 one another. 



The masses of the third class contain numerous degenerating hyphae, 

 the outlines of which are often difficult to distinguish, and mingled with 

 these are often large numbers of tiny granular bodies. Sometimes small 

 starch-grains are present among these, but they are never abundant. Often 

 the central portion of these masses is of a yellowish colour, and more dense 

 than the outer portions, which consist largely of degenerate hyphae ; in 

 fact, if it were not for the presence of this outer liyphal layer the mass 

 could be correctly referred to class 2. It should have been stated at the 

 outset that it is not possible absolutely to delimit these classes from one 

 another, as they are connected by masses of intermediate structure. 



In the cortical cells containing the bodies just described the nucleus is^ 

 frequently much sw^ollen, and it is generally observed to be in close contact 

 with the mass in the cell to which it belongs — sometimes, indeed, it appears 

 to be partly included in the mass. Usually bodies belonging to all three 

 of the above types will be seen in any one section, but one class of niasa 



