Observations on Camarosporium Abietis n. sp. 145 



or less coriaceous in texture and only rarely shiny ; such is their 

 normal dry condition, but in moist weather the}' become 

 mucilaginous and as a result have a glossy sheen. 



The young fructification seen in section (Plate III, fig. i) 

 consists of a compact mass of h}^hae breaking early through 

 the epidermis of the host. It is shortly cylindrical in shape with 

 a slightly flattened expanded base in contact srith the outer- 

 most compressed cortical tissues. The main portion of this com- 

 pacted pseudoparench\Tna is pale smoky-brown in colour, but 

 in the upper part of the fructification this merges into a distinct 

 wall some 30 to 40 /it thick composed of M'phae closely inter- 

 woven, with thick dark-brown walls and numerous cross septa. 

 In the lower part the wall gradually thins out and is no longer 

 distinguishable at the base, where the whole of the pseudo- 

 parench\Tna is of a similar character throughout. In this basal 

 tissue, and also in the central area, the h\-phal ca\ities are 

 distinct. In the lowermost part no definite arrangement of 

 hyphae is \isible, in the uppermost they tend to become 

 longitudinally arranged and later bear the young spores at their 

 apices. 



At first, spore formation is hmited to a crescent-shaped area 

 some 40 to 50 ju in depth, situated below the apical portion 

 of the wall and separated from it by a thin layer of pseudo- 

 parench\Tna which never forms spores. These when first formed 

 are spindle-shaped, one-celled, hvaJine and contain a few large 

 oil-globules of a pale oHve colour (Plate IV, fig. 5, b). Later 

 the oil-globules break up and separate cross walls are developed 

 one near each end of the cell (fig. 6) ; and soon five to ten cross 

 walls are formed. These at first are colourless but soon darken, 

 gradually taking on a brown colour. A few longitudinally running 

 walls are then developed, these being characteristically obUque 

 or cun'ed and rarelv more numerous than three per spore 

 (Plate IV, fig. 5, c and d). The walls stiU further darken, and 

 as the oil- globules retain their original colour they show up 

 conspicuoush' in the cell at this stage. 



As the spores mature they become freed by the mucilaginous 

 degeneration of the sporophores and a fresh layer of spores arises 

 below them, these being set free in a simQar manner (Plate III, 

 fig. 2) . The level of spore-formation thus spreads progressively 

 downwards until only a small area at the base of the fructifica- 

 tion remains to represent the original compact mass (Plate III, 

 fig-3.B). 



The wall of the mature spore is bronzy-brown in colour and 

 possesses a thin outer layer which is darker in tint than the 

 remainder. The spores measure on an average 30/i in length 

 by 12 /Lt in breadth, the maximum and minimum lengths and 



M.S. 10 



