298 Sketch of the Infusoria of the family Bacillaria. 



Meyen, in his Report on Vegetable Physiology, for 1837, (p. 

 54 of Francis's translation,) and also in his Pflanzen Physiolo- 

 gic, Vol. Ill, p. 437, has brought forward the fact of the presence 

 of starch, in the Closteria, as conclusive evidence of their being 

 plants. He states that the large and small globules in these bod- 

 ies "at certain times, and particularly in spring, are almost wholly 

 composed of starch." He adds that in the month of May he had 

 observed " many specimens of Closterium in which the whole 

 interior substance was granulated, and all the grains gave with 

 iodine a beautiful blue color, as is the case with starch, which is 

 not an animal product." 



In the Annals of Natural History for August, 1840, (No. 33, 

 p. 415,) is given a notice of a paper read by Mr. Dalrymple be- 

 fore the Microscopical Society of London. As this paper gives a 

 good idea of the present state of the discussion concerning the 

 nature of the Closteria, I believe that no apology is necessary for 

 taking from it the following extract, especially as my own obser- 

 vations enable me to confirm some of the statements and to cor- 

 rect others. 



" The author, after detailing the history of Closterium, from its dis- 

 covery by Corte in 1774, down to the present time, entered into a detail 

 of its appearance and general structure ; he described it as consisting 

 of a green gelatinous and granular body, invested by a highly elastic 

 and contractile membrane, which is attached by variable points to a 

 hard siliceous shell, which was afterwards stated by Mr. C. Varley to 

 resist even the action of boiling nitric acid. The form of Closterium 

 is spindle-shaped or crescentic — the shell consisting of two horns, taper- 

 ing off more or less to the extremities, and united at the central trans- 

 verse line, constituting a perfectly symmetrical exterior. At the ex- 

 tremity of each horn is an opening in the shell, which, however, is 

 closed within by the membranous envelope, wanting however in some 

 specimens. Within the shell and at the extremity of the green body, 

 is a transparent chamber containing a variable number of active mole- 

 cules, measuring from the 20,000th to the 40,000th of an inch ; these 

 molecules or transparent spheroids, occasionally escape from this cham- 

 ber, and circulate vaguely and irregularly between the periphery of the 

 gelatinous body and the shell ; further, the parietes of this chamber 

 have a contractile power. The author denied the existence of any 

 papillce or proboscides at this part, as well as the supposition of Ehren- 

 berg that these moving molecules constitute the basis of such papillae. 

 He also denied the statement of the same distinguished observer, that 

 if coloring matter was mixed with the water in which the Closterium 



