MUCOEINL 241 



ordinary glass slides ; a very little water is placed in the bottom o( the 

 cell so formed, to keep the air in it always moist ; a small drop of the 

 nutrient liquid, free from spores of any kind, is placed in the middle of 

 a cover-glass of the proper dimensions, and in this a single spore of 

 some particular Mould is placed ; the cover-glass is now inverted over 

 the cell, and held in place by a minute quantity of oil on the edge of 

 the cell. The preparation must be placed in a warm and saturated 

 atmosphere. An ordinary bell-jar set over a plate of water, or better 

 still, of wet sand, will furnish a very good moist chamber. The appa- 

 ratus used by Van TVghem and Le Monnier is, however, in many re- 

 spects the best that has yet been devised (Fig. 163). 



By means of such cultures as this, the student may follow all the de- 

 tails of the germination, and after-development of any particular 

 spore, as all that is necessary to do is to remove the slide from the 

 growing box, and, without disturbing the cell, to place it under the 

 microscope ; the same specimen may thus be examined any number 

 of times, with the least possible liability of error. 



(7i) The most common Moulds are species of the genus Mucor. M. 



Fig. 163. Section of apparatus for cell cultures. The shaded portion represents a 

 section of a tin or zinc box ; a, a, the supporting ledges ; 6, b, the glass slips ; c. c, 

 glass or metal rings fastened to the glass slips, seen in section, and covered with a 



Eiece of thin glass ; g, plate of glass, covering the box. The dotted line shows the 

 eight of the moist sand with which the bottom of the box is covered. 



Mucedo and M, stolonifer (if distinct) are common on many decaying 

 substances. M. Syzygites occurs on decaying Agarics and Polypori. 

 Pilobolus crystnllinus, PiptocepJudia Freseniina, and Chcetocladium 

 Joneaii occur on animal excrement. Phycomyces nitens grows on oily or 

 greasy substances, as old bones, oil casks, etc. 



(i) The Moulds are evidently related to the Mesocarpese in their 

 sexual reproduction, which is the most important, as it is the most con- 

 stant. The conidia of Moulds are clearly homologous with the zoospores, 

 of the Zoosporese, being nothing more than aerial modifications of them. 

 The non-septated condition of the filaments of the Moulds does not con- 

 stitute so great a difference between them and the filaments of the green 

 Conjugate as might at first be imagined ; in the germination of the 

 zygospore of Spirogyra it will be remembered that the filament elon- 

 gates quite a good deal before a septum forms in it ; between this and 

 the very late formation of septa, as in the Moulds, the difference is 

 only one of degree. The Moulds may then be looked upon as Meso- 

 carpous Conjugate which have lost their chlorophyll through their 

 saprophytic habits, and which have otherwise undergone slight modifi- 

 cations mainly correlated with their aerial habits. 



