4: THE AMERICAN MONTHLY [Jannarv. 



hyphit. Here, then, is a simple division of labor, one set of hypha^ 

 being nutritive organs, the other reproductive. 



7. Mould a Plant. — That Pencillium is a living organism has now 

 been showni by its power of growth, the forming from spores or conidia 

 of new mycelia. 



Its presence on damp and warm nutrient substance is also readily 

 understood when we jecall how light the conidia are and how they 

 float oft' as a cloud of dust. Experiments on the vitality of conidia 

 would show that their power of growth is not at all impaired by drying 

 up. and that examination of the air of closets and rooms would show 

 them to be present. We have then, in the moulding of bread, a very 

 simple condition of aftairs. as intelligible as any gardening process. 



Following the course of events from the conidium. it first sends out 

 a small tube, which growing longer and longer, branching and re- 

 branching, becomes a hvpha. then a mycelium. Later still you would 

 find this mycelium shooting up aerial hyphae, and these in turn produc- 

 ing conidia like the one we start from. Here. then, is a somewhat 

 more complicated course of life from that obsei-ved in yeast, for we 

 have the yeast buds made directly from the body of yeast ; but the 

 conidia buds arise not from the body which grows from the conidia 

 (viz., the mvcelial hypha). but from the body which grows from it (viz.. 

 the aerial hvpha). This introduces us to a degree ot complication sur- 

 passing anvthing found in yeast or in protococcus. The branching 

 and division of the threads, the new members remaining attached to 

 the mass, make possible the building up of a complex structure like the 

 mycelium. Here, as in all the fungi or moulds, the cells are never 

 formed by longitudinal division but only by transverse division. If 

 mould is an organic being or a living thing, is it animal or plant.' We 

 find that the protococcus, which can live and thrive in rain-water by 

 the power it has, through the presence of chlorophyll, can do what no 

 animal can do. It would shortly die in rain-water. Hence we can 

 separate the two bv this power through chlorophyll. But is yeast or 

 the mould an animal also.' There are reasons based on a study of plants 

 as a whole which make it imperative to consider the mould a plant, 

 but a parasitic plant, one living upon food ready-made, and not elab- 

 orating, from simple mineral sources, the complex chemical constit- 

 uents of its own protoplasmic substance. 



Conclusion. — This is hardlv the place for any discussion of the nu- 

 merous biological speculations which are suggested by Peticillhnn. 

 but it mav be said that we are here in that realm of the organic world 

 to which the bacteria are believed to belong, and that here started the 

 theory of spontaneous generation from the seemingly spontaneous 

 growth of mould, the conidia being then entirely overlooked. 



The Hoagland Laboratory, of Brooklyn, X. Y.. is now open for 

 work. The director is Dr. Geo. M. Sternberg. Dr. G. T. Kemp, of 

 Johns Hopkins University, who is associate in bacteriology and phys- 

 iology, will conduct practical courses in bacteriology and physiology 

 during the spring. The medical schools are realizing the importance 

 of thorough scientific work in the medicine of to-day, and providing 

 for it more and more extensivelv. 



