INTRODUCTION TO CRYPTOGAMTC BOTANY. 303 



stance which is well known to belong to formations older than 

 the present condition of the earth. One of these is little dif- 

 ferent from our common Penicillium ; and the other ap- 

 proaches the genus Corethropis, Cda.* Traces of other 

 genera also occur, as it is almost certain they would, if 

 moulds were in existence when the pines, which produced the 

 amber, were flourishing, as the resin to which the amber is 

 due, would entrap minute substances floating about in the air, 

 and a few seconds after embalm them, exactly as is the case 

 with gmii, which incloses the spores and threads of many 

 species and genera of Fungi, which did not originate within 

 their substance. A fragment, for instance, of the gum of 

 Cerasus serotina exhibited the spores of a Pestalozzia and 

 Hypoxylon, and more would, doubtless, have been found, had 

 the examination been undertaken with the especial view of 

 detecting such matters. Movilds occur abundantly in the 

 apricot or cherry gum of our country. -f* Sclerotia are formed 

 also at the expense of the genus Mucor, as was proved by 

 myself and Mr. Hoffman, by causing a Sclerotium to germinate 

 in a drop of water, surrounded by a pellicle of air, into which 

 the fertile shoots could protrude. In a single species, Spori- 

 desmium paradoxumv] Corda observed spiral tissue in the 

 cells which constitute the spores, like that which occurs in 

 the aerial roots of orchids, in anthers, &c., only on a very 

 small scale. 



* See Ann. of Nat. Hist., N.S., vol. ii., p. 380. What is figiu-ed there 

 as a species of Streptothrix, is probably not organic, but due to the 

 motion of bubbles of air in a highly resisting medium. 



t Gum tragacanth, which occurs in the form of tendrils and of flakes, 

 is certainly organised, as described and figured by Kiitzing. Both ex- 

 hibit large rounded sacs, consisting of several coats, inclosing a cavity 

 containing starcli granules. The walls of the sacs are composed of cel- 

 lulose. Intermixed is a considerable quantity of mycelium. Thei-e is 

 not the slightest reason to believe that the production is allied to 

 Fungi. For a fuller account, see Gard. Chron., 1855, under Vegetable 

 Pathology, No. 65, where information will also be found about the 

 occurrence of Funo-i in gum. 



