THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL 



YOL. III. 



New Yoek, Maech, 1882. 



No. 3. 



Reproduction of Closterium by 

 Swarm-spores. 



BY FRANK HOLLAND. 



In works on the microscope, it is 

 sometimes stated that besides the two 

 usual methods of reproduction of the 

 Desmidiaceae, division and conjuga- 

 tion, there is sometimes a third meth- 

 od, by means of zoospores or swarm- 

 spores. 



While looking over a drop of water 

 from a fresh-water gathering, last Au- 

 gust, 1 found a desmid of the genus 



Fig. 9. 



Closterium, which I think was repro- 

 ducing itself by swarm-spores. In 

 the hope that my observations will 

 draw out more information on the 

 subject from the readers of this 

 Journal, I record them as follows: 



When I first saw the Closterium it 

 had the appearance of fig. 8, all the 

 endochrome evidently having been 



used up in making the greenish, oval 

 bodies seen within the cell. 



It was early in the forenoon that I 

 saw the desmid, and as it presented 

 such a remarkable appearance, en- 

 tirely different from anything I had 

 ever seen before in Closterium, I de- 

 termined to study it, to learn, if possi- 

 ble, into what the bodies would de- 

 velop. All through the forenoon it 

 presented the same appearance, but 

 in the afternoon, when I sat down to 

 my microscope, I found there had 

 been a change; some rounded points 

 had grown out through the 

 walls from the oval bodies 

 within, each oval body seem- 

 ing to have one, as shown in 

 fig. 9 a, and also in fig. lo a. 

 These points were trans- 

 parent, the outlines of the 

 walls being the only indica- 

 tion of them, and they were 

 apparently destitute of proto- 

 plasm. For sometime, an 

 hour or so, the desmid re- 

 mained in this condition, 

 after which balls of granular 

 protoplasm (fig. 9, b and c, 

 shown more enlarged in fig. 

 ii) shot out very suddenly 

 from the ends of the points — 

 they were round at first, as 

 at b, fig. 9, and then changed 

 in a few minutes into a some- 

 what irregular mass, as at c, fig. 9. 



The irregular masses kept changing 

 to more irregular forms, from which 

 the swarm-spores gradually grew ; 

 small masses of the protoplasm seemed 

 to condense from the mass and to ab- 

 sorb the rest of it as they grew, until 

 finally they attained the lenticular 

 forms seen in the two round masses 



