THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



Vol. IV. 



Boston, December, 1883. 



No. 12. 



About Moulds. 



Sometimes when we look at the 

 most simple organisms in existence 

 we think they are the most beautiful. 

 One can scarcely tell which is most 

 wonderful, the complex structure of 

 the higher plants and animals, or the 

 manifestations of life in its primitive 

 conditions. In one the various func- 

 tions of life are performed bv differ- 

 ent organs, each perfectly and beauti- 

 fully adapted to its purpose, in the 

 other there are no organs, and 

 scarcely any distinction between the 

 outside and the inside ; yet there is 

 life in all its perfection in the merest 

 speck of seemingly homogeneous 

 jelly. 



Imagine a forest in miniature, so 

 small indeed, that hundreds and thou- 

 sands of trees would grow in the space 

 of a few hundredths of an inch. It 

 would be beautiful under a microscope 

 to see how the micro.scopic stems 

 stand up from the mass of interlacing 

 roots, and branch out in all directions 

 at the top. A growth of some of the 

 microscopic fungi commonly known 

 as moulds, may be likened to such a 

 forest. The comparison is not scien- 

 tifically exact, perhaps, yet it will 

 serve our purpose very well. The first 

 stage in the growth of a mould is a 

 mass of white, interlacing fibres, which 

 spread with great rapidity all over the 

 mouldy surface. But, perhaps the 

 reader will say, moulds are not 

 white, — they are blue, or pink, or 

 black, or red. It is true that we usu- 

 ally do observe moulds more or less 

 colored, but this is because we over- 

 look them until they have matured 



their fruit, which is colored. In their 

 first stages they are white, and the 

 part that first appears always remains 

 white. This part is called the myceli- 

 um. The mycelium is always white, 

 and it does not change this character 

 at any time. It consists oT a series 

 of cells joined end to end, forming 

 filaments. These may be compared 

 to the roots of our miniature forest, 

 only, instead of lying hidden beneath 

 the ground, they often spread over the 

 surface, forming a delicate, cottony 

 layer, from which the trees will spring 

 up here and there. They also pene- 

 trate into the interstices of the article 

 on which they grow, and thus rapidly 

 spread through it, causing it to decay. 

 Before going any further with our 

 description, it will be best to tell how 

 a mycelium for study may be obtained. 

 It is easy to obtain a piece of mouldy 

 bread, or cheese, or boiled potato, 

 or some mouldy article of food. The 

 greenish or bluish laj'er that forms 

 on the surface of preserves will be 

 excellent for the purpose. Having 

 obtained such an article, take a slice 

 of potato, raw or boiled, it makes 

 no difference, or a bit of bread, and 

 dust some of the blue mould over it, 

 or put it against the mouldy surface 

 so that some of the minute particles 

 of the mould will adhere to it. Then 

 take a small bell-glass, or a tumbler, 

 and a saucer of water. In the saucer 

 put a small, wide-mouthed bottle, and 

 upon that a piece of glass, and on the 

 glass place the potato or bread. 

 Then line the tumbler with a strip of 

 blotting-paper, and invert it over the 

 saucer. The object of all this is to 

 keep the specimen in a moist atmos- 



