102 DIVISION I. GENERAL MORPHOLOGI'. 



The episporium of some Ustilagineae, especially Ustilago receplaculorum, shows 

 also a broad pellucid mark covering ^ or ^ of the circumference of the spore, and 

 corresponding to a thinner spot which passes gradually into the thicker and darker 

 coloured wall around it. 



Lastly, we may mention the delicate striae on the ovoid spores of Ascobolus 

 furfuraceus and its allies. These, according to Janczewski, are thin places in the form 

 of longitudinal slits which do not penetrate through the whole of the substance of the 

 violet-coloured episporium, and often form acute-angled anastomoses. The colour- 

 less endosporium is smooth, homogeneous, and with its surface unbroken *. 



The various lamellae and strata of the spore-membrane, of which we have 

 hitherto been speaking, are developed, as far as our present observations go, in the 

 same mode and succession as those of vegetable cell-membranes generally ; there is no 

 reason therefore for entering further in this place into the details of their develop- 

 ment than has been done in previous sections. 



Besides the membranes, which have now been described, the spores of 

 many Fungi have on their surface envelopes or appendages formed of a colour- 

 less transparent gelatinous substance, which swells greatly and usually dissolves and 

 disappears under the influence of water, and shrivels up when treated with reagents 

 which withdraw water. They may be termed gelatinous envelopes or gelatinous 

 appendages. They are found alike in spores formed in asci and in acrogenous spores, 

 in simple and in compound spores. 



The ascospores of many of the Sphaeriaceae, as Massaria 2 , some species of 

 Sphaeria 3 , Xylaria pedunculata first mentioned by Berkeley *, and Fuckel's Hypo- 

 copreae and Coprolepeae, are surrounded with a gelatinous coating of varying depth 

 and with vejy faint circumscription. A similar structure is found in Rhytisma Androm- 

 edae, Hysterium nervisequum, and other Hysterineae. The compound spore of 

 Sphaeria Scirpi is enclosed in a delicate transparent sac, which fits close to its sides 

 but is prolonged at either end into a long conical appendage 8 (Figs. 46, 49). 

 The spores of many other Sphaerieae, species for example of Valsa and Melanconis 6 , 

 have a subulate appendage or a semicircular knob at their extremities. A semilen- 

 ticular gelatinous appendage is found on the episporium on one side of the 

 round spores of Peziza melaena and the ovoid spores of Ascobolus furfuraceus, 

 P. and several of its nearest relatives 7 , which swells into a hemispherical or spherical 

 shape when the spores are discharged in water ; Peziza convexula and Ascobolus 

 immersus, P. 8 have the entire episporium encircled by a broad gelatinous coat. The 

 common envelope, which encloses as in a sac the 8 or 16 spores in the ascus of the 

 forms of Ascoboli distinguished as Saccoboli, must also be mentioned in this place. 



Among acrogenously produced spores those of the' plant known as Myxocyclus 



1 See Boudier, 1. c. on page 92. Janczewski in Bot. Ztg. 1871, p. 768. 

 3 Fresenius, Beitr., and Tulasne, Carpol. 



3 Sollmann in Bot. Ztg. 1862, 1863. 



4 Mag. of Zool. and Bot. II, p. 324 (1838) ; see also Tulasne, Carpol. II. 



5 Pringsheim's Jahrb. I. t. 24. 



8 Tulasne, Carp. II. Fresenius, Eeitr. t. VII, 22, 21. 

 7 Boudier in Ann. d. sc. nat. ser. 5, X. 

 * Coemans, 1. c. on page 92. 



