ZOOLOGICAL AND BOTANICAL ASSOCIATION. 103 



as animals. The principal reasons advanced by the Ehrenbergian school 

 for surrendering this group to the zoologist, are, that they exert a volun~ 

 tary motion ; that they increase by transverse self-division ; and that 

 in Closteriura there are at the extremities apertures and protruding 

 organs continually in motion. "With regard to the first reason, it is clear 

 that using the term " voluntary" is a begging of the question. That 

 they move is beyond doubt, for these organisms, if buried in the mud, 

 will come to the surface and become exposed to the light. While this 

 is doubtless a highly curious phenomenon, it strikes me as not more 

 remarkable than any flowering plant cultivated in-doors bending its 

 leaves towards the window under the stimulus of light (not to speak of 

 the vigorous movements of unquestionable plants high in the scale). As 

 to the second reason, the increase by transverse self-division, — this is 

 by no means an exclusively animal characteristic ; the very same argu- 

 ment might, with greater force, be applied in proof of their vegetable 

 nature, as I need hardly insist on. "With regard to the third reason, — 

 the various species of Closterium have been too often made the subject 

 of examination by numerous observers to allow of terminal apertures 

 and protruding organs not having been seen, if they really existed. 

 There can be no doubt that they do not. At each extremity of the Clos- 

 teria, however, there is a distinct chamber or space containing active 

 moving granules constantly flitting about ; what they mean, or what 

 their purpose or import, is as yet unexplained. It may be that they 

 are merely passively tossed about by the eddy which is likely to be pro- 

 duced by the conflicting currents of protoplasm, which are so evident 

 and so curious in Closterium. But a very similar circulation occurs in 

 Penium digitus, but here, notwithstanding the current, there is no open 

 clear space at the ends containing moving granules. In that species, 

 however, there are moving granules to be seen travelling over the surface 

 of the mass of endochrome, which sometimes make their way down the 

 frond, at one side, to the end, where they follow its curve and come up 

 by the other side, which looks like as if these granules were carried by 

 the current, which is, however, apparently of an irregular character like 

 that in Closterium. But, again, it is no uncommon thing to see the 

 broken-up granular contents of a Closterium pressed-out upon a slide, 

 to exhibit the same agitated dancing motion as a few possessed within 

 the living frond ; and I have seen (it was in Closterium lanceolatum), 

 in a specimen from which the contents had nearly all been pressed-out, 



