SPECIAL MORPHOLOGY: ALG.E. 



149 



rials, which he handles according to a principle of unity, by which we 

 are enabled to compare separate observations with each other, and trace 

 their mutual relations. And we must not conceal that it is extremely 

 difficult, owing to the external relations, to make comprehensive obser- 

 vations upon the law of development, and that consequently the re- 

 proaches which we must make against the state of the science in regard 

 to the Algce in our day, only apply to a certain extent to the individual 

 investigations. In some degree, certainly, the cause lies in the artificial, 

 senseless methods of research that infect the whole science of Botany, 

 which has hitherto directed its attention far more to herbaria than to 

 living plants ; and hence, those who live far inland become Algologists, 

 whilst botanists residing near the sea-side busy themselves in describing 

 some little dried Jungermannia brought from Java ; and European in- 

 vestigators thus too often devote more attention to tropical plants than 

 to those that are indigenous to their own country, and are in their own 

 immediate neighbourhood. 



The so-called copulation of Spirogyra and a few other Conferva 

 (fig. 121.) are generally represented as especially remarkable. They consist 



121 



of thread-like cylindrical cells arranged in a linear series. At a definite 

 time one side of each cell expands into a papilla, which combines with 

 any papilla of another cell of the same or another filament with 

 which it may come in contact, and then the partition is absorbed, the 

 contents of the one cell pass over into those of the other cell, and out of 

 the total mass a spore is formed (fig. 121. a a). I have observed the 

 following cases, which prove how inessential this process really is. Two 

 cells were combined with the papilla of a third cell ; and thus arose four 

 spores, one in each of the first-named cells, and two in the third. Three 

 cells were combined, and the result was the formation of one spore in 

 the space formed by the three papilla. Again : two cells were combined, 

 in the one of which there appeared two spores, and a third spore in the 

 cavity of the papilla. Two cells combined together, and here a spore 

 was formed in each one (fig. 121. c). Another instance very frequently 

 occurred in which one cell, that had a papilla which did not combine 

 with another, exhibited a spore formed within the cell (fig. 121. b b). 

 Finally, it sometimes happens, although but rarely, that a spore is formed 

 without the cell having borne any papilla. 



The Algce certainly merit the most thorough examination, as we are 



181 Zygnema quininum. Phenomena of the so-called copulation. At a a, the con- 

 nexion is effected, and the contents, being transferred from one thread to another, form a 

 spore. At b b, the projections are formed, without, however, their being able to com- 

 bine with another cell ; notwithstanding which, a spore is formed. At c, a spore is 

 formed, and here another prolongation effected, which is connected with another cell, in 

 which the contents begin at the same time to concentrate themselves into a spore. 



t 3 



