168 THE MICROSCOPE AND ITS PREPARATIONS. 



by some bristling branching hairs. Through this mouth and 

 into the cavity of the utricle, quantities of microscopic insects, 

 water fleas, and animalcules, in some way or other find their way, 

 and are there digested and absorbed with the exception of their 

 hard parts. What brings so many of the tiny denizens of the 

 water to crowd themselves into these uninviting little prison 

 houses, is I think still a good deal of a mystery. The prey 

 caught is indiscriminately animal and vegetable eating organisms, 

 and even larvae and floating pollen grains. So that it cannot be 

 a secretion of any kind which attracts so various an assemblage 

 of aquatic animals and things. The bristles around the mouth 

 are so arranged as to form a kind of open-work funnel, conduct- 

 ing directly to the valve which closes the mouth. The writers 

 on the subject, Darwin and others, seem to think that chance and 

 curiosity alone conduct the prey to and into the orifice. I hardly 

 think that these would account for the presence of all and so 

 many of the things which, as you will have an opportunity to 

 see for yourselves, are found within the bladders. I think that 

 the lid is sensitive to the touch or irritation of anything lying 

 upon it, and opens with a quick motion, engulfing whatever may 

 be near it. We have plenty of instances of such sensitive 

 movements in other plants of similar habits. 



But how strange it is that down in the water there should be 

 this little carnivorous vegetable, lying in wait for its prey, and 

 like a great shark ready to turn up its mouth and swallow any- 

 thing and everything that happens to come along. Really our 

 ideas of the distinction between animals and plants are quite 

 disturbed by the performances of these animal-eating plants. 



I have here a preparation of a small portion of the fruiting 

 stalk of a greenhouse fern, called Aneimia Mexicana. It pro- 

 duces its spores on a stalk which grows up from the top of a leaf 

 stalk, and the spores are like the pollen grains of the mallows 

 and abutilons ; in both which respects it is quite unique and 

 remarkable among ferns. It makes a very beautiful object under 

 dark field illumination, as I will show you later in the evening. 

 It is a very pretty experiment to place the spores of a fern on a 

 piece of porous sandstone, partly immersed in a saucer of water, 



