COPRINUS STERQUILINUS 229 



the spores continued to grow {vide infra, Fig. 106, p. 250). Then 

 one of the spores was violently propelled away from its sterigma 

 and, in its flight, took with it part or the whole of the drop and 

 another spore. The two spores, separated by the drop, after settling 

 on the slide, dried up, and the spores were left on their sides in the 

 position they first occupied when they fell on to the slide. 



Now, as already mentioned in a previous Section, ^ the more 

 rounded side of a spore of Coprinus sterquilinus , i.e. the side which 

 is always directed downwards when the spore is falling through the 

 air and which becomes the keel when the spore is drying and be- 

 coming boat-shaped, is covered by a colourless wall in the form of a 

 concavo-convex meniscus (Fig. 95, a in A), Therefore, when a spore 

 settles on a slide or on a blade of grass, it is this colourless meniscus 

 which comes into contact with the suhstratvmi (Fig. 95, E, K). The 

 meniscus is highly adhesive and, upon drying, sticks the spore very 

 tightly to the substratum ; for, when spores have settled and dried 

 on a glass slide or a blade of grass, one cannot shake them off, how- 

 ever much violence may be used in the attempt and, as experiment 

 showed, they cannot be dislodged by water in the form of continuous 

 artificial rain, even when the rain is allowed to fall for twenty-four 

 hours. As further evidence of the adhesiveness of the meniscus it 

 may be mentioned that, if a spore has settled and dried on a glass 

 slide and one dislodges it with a needle, a piece of the meniscus 

 is often left behind on the surface of the glass, thus allowing one 

 to perceive where the spore was attached before it was disturbed 

 (Fig. 95, N). 



The spores of Coprinus sterquilinus in a thin spore-deposit on a 

 glass slide can be dislodged by a normal solution of sodium hydroxide 

 but not by hot water, chloroform, alcohol, or concentrated nitric 

 acid. Evidently the meniscus is not dissolved either by water or 

 by many other chemical substances. 



Coprinus sterquilinus, as we have seen,^ is a coprophilous fungus 

 which is normally found on horse dung. Now its occurrence on 

 horse dung depends upon the fact that the spores settle on grass 

 and are swallowed with the grass by horses : the spores pass un- 

 injured down the alimentary canal of any horse which has swallowed 

 . 1 Vide p. 221. 2 yi^^ p, 179, 



