CHAPTER III. — SPORES OF FUNGI. 105 



affected even by concentrated sulphuric acid, the less so as a rule in proportion to the 

 depth of their colour, and, as might therefore be expected, the episporium usually less 

 than the endosporium. Others swell more or less strongly in sulphuric acid or 

 wholly disappear. In very many cases the application of concentrated sulphuric 

 acid is an excellent method of showing the minuter structural characters of the 

 episporium, partly because it is rendered more transparent, partly because the other 

 parts are destroyed or stand out from the episporium, which either bursts of itself or 

 is readily made to burst. 



Coloured episporia are usually more or less destroyed by boiling in potash ; the 

 reticulately thickened episporium of Tuber aestivum is entirely destroyed by this 

 means according to Schacht 1 , as is also the finely warted outermost lamella of the 

 spores of many Uredineae 2 . These membranes therefore resemble to some extent the 

 cuticle of the higher plants in their behaviour with reagents; but it has still to 

 be determined whether they agree with it in other respects also, and are therefore 

 of the nature of cork. 



With a few exceptions, to be mentioned presently, spore-membranes are coloured 

 yellow with iodine and sulphuric acid after maceration with potash or Schulze's 

 solution, or, if not, are not coloured blue, resembling in this respect the majority of 

 fungal hyphae. 



These remarks apply to the single, simple spore in the strict use of the term, 

 and to the compound spore also. 



The gelatinous envelopes and appendages and the other gelatinous lamellae of 

 which we were just speaking are affected by l-eagents in the same way as similar 

 bodies in other organs and classes of plants. They are as a rule very perishable and 

 soon disappear if the spores are sown in or on water. 



The coloured episporium of the Ascoboli carefully studied by Boudier and 

 Janczewski (1. c. on page 102) has peculiar characteristics which we must not attempt 

 to describe in this place. 



The entire membrane of the acrogenously produced spores of Peronospora 

 behaves in exactly the same way as the cellulose of the higher plants towards iodine 

 and sulphuric acid. Dilute solution of iodine is the only reagent which colours the 

 whole of the spore-wall of Currey's Amylocarpus and the gelatinous envelopes of the 

 spores of Xylaria pedunculata 3 an intense blue. The outermost lamella of the episporium 

 of the spores of Corticium amorphum, Fr. (Fig. 30) with slender spike-like warts 

 is coloured a beautiful bright blue with watery solution of iodine, and dark blue 

 with iodine and sulphuric acid ; the spike-like processes share in the coloration, 

 but the inner thicker lamella of the episporium and the endosporium remain 

 uncoloured. 



The protoplasm of the spores of the Fungi is either dense and apparently 

 homogeneous, or it has a greater or less number of granules or drops of oil dis- 

 seminated through it, and in most cases appears to be colourless when a 

 single spore is examined under the microscope : in a few cases only it is coloured 

 by embedded pigments. 



1 Anat. u. Phys. II, 193. 2 De Bary, Brandpilze. 



3 Tulasne, Carp. I, II. 



