= ae: oa, eS 
O,, the vast territory of the freshwater alge, which was shrouded in 
almost total darkness no longer than twenty years ago, as to the know- 
ledge of their development and systematic arrangement, the excellent 
researches of PrinesHem, Conn and Dr Bary have thrown an unexpected 
light. The profound morphological inquiries of these men have enriched 
science with the knowledge of a not inconsiderable number of orders of 
algz, more nicely distinguished from each other and of much greater 
importance and interest, on account of the history of their development, 
than most other orders of plants. Nevertheless a great number of alge 
still remains almost unknown as to the history of their development and 
their place in the system. Among these are to be counted the Clado- 
phoree, existing as well in salt and brackish, as in fresh water, and extre- 
mely rich in varying forms. We have, however, believed we knew, 
that their propagation was effected, as a rule, by naked, moving, ciliated 
spores, — so-called zoospores. This is indisputably the case with many, 
or perhaps with most of the plants that have been counted among the 
Cladophoree. But that this is not the case with all the forms that have 
been referred to this genus, is proved by the researches of which I 
am now going to give an account. 
My attention was directed to Cladophorew during a sojourn at the. 
magnificent botanical institution at Kew in England, in the summer of 
1872, by an alga which occurred in great abundance in its Tropical 
Aquarium, or the so-called Waterlily-house. It resembled in its general 
habitus a common Cladophora, but was distinguished by most of the 
specimens having, besides the common long and slender cylindric cells, 
others somewhat swollen, short, and very rich in chlorophyll, which 
were almost always single, and most frequently alternated in a regular 
Nova Acta Reg. Soc. Sc. Ups. Ser. III. 1 
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