1887.] in the Neighbourhood of Simla. 365 



is very distinct with now hlack points, the dried up spermogonia, over 

 it (Fig. 4, PI. XIV), and then the epidermis covering the surrounding 

 cushion tears circularly near the external margin of the cushion and curls 

 up inwards towards the centre disclosing a bed of white secidiospores {see 

 left-hand patch in Fig. 4, a. and 6.). The spermogonia, which are extremely 

 superficially placed (see Fig. 6, PL XIV.), are thus situated on the under 

 surface of the leaf only. They are of the usual form and structure with 

 a tuft of paraphyses protruding through the mouth. The whole organ, ex- 

 cluding the paraphyses, measures about 50 /x in depth and 100 /n in breadth. 

 The cecidiospores, when just wetted with water, measure from 22 x 20 />t 

 to 19 X 18 /-i, the average of several measurements being 21 x 192 /*. 

 The spores are colourless and almost round (Fig. 5, a. PI. XIY.) with an 

 epispore densely studded with minute tubercles. The distribution of 

 the mycelium is peculiar and deserves description. In a section of a 

 leaf passing through the gecidium, it will be seen that the mycelium 

 lies mainly in two strands, one under the upper epidermis, between it 

 and the palisade-cells, the other and larger under the lower epidermis, 

 between it and the spongy cells (Fig. 6, PI. XIV.). Moreover, the charac- 

 ter of the layer of hyphae under the upper epidermis is of a somewhat 

 looser, more pseudo-parenchymatous character, than that under the 

 lower epidermis (Fig. 7, PI. XIV.). It should be noted that these 

 layers of mycelial filaments are composed solely of hyphae without any 

 part of the host tissue being involved within them, and thus resemble 

 strikingly the non-algal parts of lichens. The palisade-cells and spongy 

 tissue between the two layers of mycelium are indeed extremely little 

 affected or altered in any way. While in unaffected normal places the 

 length of the palisade-cells is about 60 /u., and the depth of the spongy 

 tissue layer about 50 /x, these measurements within attacked areas are 

 about 56 /x and 36 /x, thus showing some diminution in size, especially 

 in the spongy layer. The lower mycelial layer is about 50 fx in depth and 

 the upper layer only 24 /x. The secidial fructification is, as it were, 

 inserted within the lower mycelial layer {see Fig. 6, PI. XIV.), some 

 strands passing above it and some below it. The peridium consists of 

 a layer of cells about 32 X 30 /x in size, forming only a roof to the 

 extremely large circular secidium (see Fig. 6, PI. XIV.). These cells 

 are very loosely attached to one another, readily becoming isolated. Such 

 an isolated cell is shown in Fig. 5, h. PI. XIV ; and this figure also shows 

 that it is beset externally with tubercles. The secidiospores are given 

 off in rows from a pseudo-parenchymatous hymenium without any well 

 defined basidia, and have no intermediate cells between successive spores 

 (Fig. 6, PI. XIV.). The eecidiospores, as seen in rows in sections of leaves 

 that have been hardened in absolute alcohol, are cubical (Fig. 6, PI. XIV.). 

 47 



