204 



THE POPULAR SCLEXCE MONTHLY. 



Fig. 



-Eohinella Flabellata, a fan-like 

 marine diatom. 



hours of patient labor which it cost to bring out so much, as one 

 little turn of the inner canal whose windings hold the living and 

 active part of the plant, and also the explanation of the manner 

 in which it moves. He has studied the mechanism of several 

 forms and made models of plaster of Paris, and others of wire. 



Pinnularia major (see Fig. 2) is 

 the plant from which the most 

 conclusive results were obtained, 

 and he claims to have demon- 

 strated the existence of aper- 

 tures on the surface of the shell 

 through which the protoplasm 

 may protrude. He does not, how- 

 ever, claim to have actually seen 

 the protoplasm on the outside of 

 the shell, but holds that, accord- 

 ing to other known facts, it must 

 be forced out, though in very small quantities. These apertures 

 do not open directly into the interior, but by a series of winding 

 canals whose action prevents the too easy expulsion of the con- 

 tents. The movement of this protoplasm along the lines between 

 the openings causes the movement of the diatom in a similar 

 manner to the action of the fins of fishes. All this labor, after 

 all, has reference only to a certain class of these plants ; there are 

 many others of such different forms that much study will yet 

 have to be expended on them before their secrets are laid bare. 



There are some curious little forms which grow in clusters on 

 stem-like bodies which are often fastened by their other extremi- 

 ties to some object in the water. Some of these are shown in 

 Figs. 6 and 7 ; and, finally, a variety of miscellaneous forms may 

 be seen in Fig. 8. 



There are large collections of these plants in nearly all the 

 large herbaria of Europe, and the manner of preparing them for 

 such collections may almost be said to form a special branch of 

 industry. Experts are able to mount and arrange in order hun- 

 dreds of these little organisms under a circular cover-glass of 

 about five eighths of an inch in diameter. The dexterity which 

 these experts acquire in the use of instruments is something 

 almost as marvelous as the organisms themselves. It must be 

 remembered, however, that this mechanical labor has nothing to 

 do with the work of the scientist who studies the plant. It would 

 be impossible for an investigator to give enough time to enable 

 him to acquire this skill. A gentleman in Wedel, Holstein, has 

 acquired a great reputation in this kind of work, and has plates 

 holding from four to sixteen hundred different forms. These cost 

 from twenty dollars upward, and he has recently finished a plate 



