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OBSERVATIONS ON DESMIDIAOE^, WITH A LIST 

 OF SPECIES FOUND IN TASMANIA. 



[By E. D. Haerop.] 



These beautiful plants are of an herbaceous green color, 

 and belong to the Cryptogamic division of the vegetable king- 

 dom. They have attracted attention not only on account of 

 the striking beauty and variety of their forms, but also by 

 reason of the doubt as to their position, whether in the animal 

 or vegetable kingdom, having caused considerable discussion 

 amongst learned algologists. They are now almost univers- 

 ally assigned to the vegetable kingdom. The presence of 

 starch in the ludochrome, and their mode of conjugating, 

 constitute incontestable proofs of their vegetable organisation, 

 notwithstanding the arguments of Professors Ehrenberg, Dal- 

 rymple, and Bailey to the contrary. 



The principal arguments in favor of their animality are 

 passed in review by Ealfs. They are, — first, the power of 

 voluntary motion that they possess ; second, their increase by 

 voluntary division ; third, the definite organ, possessed by 

 some genera, in which active molecules appear to enjoy an 

 independent motion, and the parieties of which appear capable 

 of contracting upon its contents ; fourth, the swarming motion 

 which takes place at a certain stage of their growth. Other 

 arguments have been advanced in support of this side of the 

 question, and Ehrenberg went so far as to describe orifices, 

 having protruding organs or feet immediately behind them, 

 the basis of such organs being the moving molecules which 

 are always opened at the ends of the Closterium. Notwith- 

 standing the great improvement in the microscope since the 

 time of this distinguished Professor, his observations have 

 never been corroborated, and there is little doubt but that in 

 this instance he allowed his imagination to overrule his general 

 accuracy. 



The power of motion and increase by self-division have now 

 been abandoned as proofs of animality. It is manifest that 

 they can transport themselves or, perhaps are transported 

 under the subtle influence of light, from one place to another ; 

 for if a mass of Desmidieae be placed in a glass vase, the one 

 side of which is exposed to the sun's rays, we shall find, after 

 a short time, that most of them have found their way to the 

 illuminated side of the glass. Professor Bailey also writes, — 

 *' I have had species of Closterium and Euastrum confined in 

 a compressor, in water perfectly free from other bodies, and 

 they moved so fast that I found it impossible to sketch their 

 forms with the Camera Lucida until they were killed." I 



