84 Dr. F. Cohn on the Development and Propagation 



after. The germination took place still more quickly in sub- 

 sequent third and fourth experiments, wherein it occurred in 

 forty-eight hours, with spores which up to that time had been 

 kept in the herbarium. I am quite unable to explain the enig- 

 matical hastening of the germination in the spring months ; it 

 could scarcely have depended on the greater heat, for the room 

 was heated to a higher temperature during the winter. At the 

 same time the germination of the Sph(eroplea-s\)oreB occurred 

 relatively rarely in cultivation, so that it went on through many 

 weeks, and the majority of the spores still remained unchanged; 

 while in the natural locality, the potato-field above mentioned, 

 by the middle of April, about which time the field was again 

 flooded, the spores had all germinated, and no trace of the red 

 felted mass remained, while the standing water was full of the 

 green filaments of Sphceroplea. 



The germination of the spores of Spharoplea difi'ers from 

 everything formerly known of the development of the Algae and 

 of plants generally ; on the other hand, it agrees surprisingly 

 with simultaneous observations on the germination of Bulbo- 

 chcete^ already published by Pringsheim in these Reports. The 

 youngest germs of Sphceroplea that I perceived were spindle- 

 shaped corpuscles from y|^ to yj^ of a line in diameter, and 

 about ^:q of a line long, running out at both ends into long- 

 filiform points which were irregularly curved and twisted, and 

 increased the total length to -^:^ of a line and more. These ger- 

 minating plants resembled in shape, even indistinguishably, 

 that interesting species of Closterium which Ehrenberg has de- 

 scribed and figured as C. rostratum. The contents of the germ 

 displayed every intermediate stage from the red of the spore to 

 the green of the developed plant; the red and green were 

 mingled in a most elegant manner, either with the red oil-glo- 

 bules accumulated at one end and the green chlorophyll at the 

 other, with a colourless band separating them in the middle ; or 

 bands of red and green alternated ; or the whole contents were 

 green sprinkled with red globules. At first sight of these germs, 

 I perceived that their dimensions were much smaller than those 

 of the spores from which they must have been produced ; hence 

 they evidently must have originated from a part, not the whole, 

 of the spore. Added to this, I never found a germinating plant 

 sticking in the membranes of the spore, but always scattered 

 free in all parts of the water ; so that I was necessarily driven to 

 the conjecture that these portions must have been discharged 

 from the spores as " swarming-cells." I was soon enabled to 

 confirm my conjectures by direct observation, 



* Ann. Nat. Hist. Ser. 2. xv. p. 349. 



