HIGHEK FORMS OF FUNGI. — LIVERWORTS. 



365 



nothing else than the organs of Fructification ; the nutritive 

 apparatus of these plants being composed of an indefinite Mycelium, 

 which is a filamentous expansion (Fig. 175) composed of elongated 

 branching cells (a), interlacing amongst each other, but having no 

 intimate connection ; and this has such an indefiniteness of form, 

 and varies so little in the different tribes of Fungi, that no deter- 

 mination of species, genus, or even family, could be certainly made 

 from it alone. From the recent researches of Prof. Oersted upon 

 Agaricus variabilis, it appears that the true Generative process 

 in the Agarics and their allies is carried-on in this mycelium ; and 

 that what has hitherto been considered as their Fructification is 

 really a mass of gemma 1 -, like the Urns of Mosses and the Thecee 

 of Ferns, which, as will be shown hereafter, are products of the 

 Sexual union which takes place in the earlier stages of the exist- 

 ence of those plants. This, if confirmed, will prove a most important 

 discovery.* — The whole history of the development of the Fungi, and 

 the question of the relationship of its different forms to each other, 

 is one that most urgently calls for re -examination at the present 

 time, under the guidance of our recently-acquired knowledge, and 

 with the assistance of improved instruments of Microscopic 

 investigation; and whilst there is a wide field for the labours of 

 those who possess instruments of but moderate capacity, there are 

 several questions which can only be worked out by means of the 

 highest powers and the most careful appliances which the practised 

 Microscopist can bring to bear upon them.f 



272. The little group of HepaticcB or ' Liverworts,' which is 

 intermediate between 

 Lichens and Mosses — 

 rather agreeing with the 

 former in its general 

 mode of growth, whilst 

 approaching the latter 

 in its Fructification — 

 presents numerous ob- 

 jects of great interest to 

 the Microscopist ; and 

 no species is richer in 

 these than the very com- 

 mon Marchantia poly- 

 morpha, which may often 

 be found growing between 

 the paving-stones of 

 damp court -yards, but 

 which particularly luxu- 



FlG 



Frond of Marchantia polymorpha, with 

 gemmiparous Conceptacles, and lobed recep- 

 tacles bearing Pistillidia. 



* See " Quart. Journ. of Microsc. Science," Vol. viii., N.S. (1868), p. 18. 



t For an example of what has to be done in this direction, see the 

 magnificient work of MM. Tulasne, entitled "Selecta Fungorurn Carpo- 

 logia," Paris, 1861. 



