ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 63 



Algological Prophecy Fulfilled.* — F. S. Collins announces the 

 fulfilment of a prophecy made by Lagerheim some time ago, when 

 describing Chsetomorphn herbipolensis, at that time the first fresh-water 

 species of the genus. Lagerheim said that the desmids he had studied 

 on specimens of aquatic phanerogams, collected long ago by B. 1). Greene 

 in Massachusetts, indicated that the algal flora of Massachusetts was of 

 almost a tropical character, and that fresh-water species of Chaetomorpha 

 were to be expected there. Since that time F. S. Collins has described 

 another fresh-water Clmtomorpha, C. chelonum, which was growing on a 

 turtle in Michigan, and he has searched for further material in many 

 ponds in New England, but in vain. Now he finds a turtle on the 

 banks of the very pond from which B. D. Greene collected his desmids, 

 and on this turtle's back is the fresh-water species of Chaetomorpha, for 

 which he had hunted so long. Lagerheim's prophecy, therefore, that 

 fresh-water species of Chaetomorpha should be found in Massachusetts 

 was fulfilled by the finding of it in the very same pond as the desmids 

 which he had examined, and which had led him to utter the prophecy. 



Phytoplankton of the English Lake District. t—W T . and G. S.- 

 West conclude their account of the phytoplankton of the English lake 

 district. Species of Flagellata and Peridinieae are recorded, and then 

 the authors devote a section to the peculiarities of the English lake- 

 plankton. They state that it contains a varied assortment of algas, 

 <il p.c. of which belong to the Cklorophyccai, 21 p.c. to the Bacillariea?, 

 and only 'J '5 p.c. to the Myxophycere. The total is 188 species and 

 20 varieties. Of 120 species of Chlorophyceas, 96 are desmids, so that 

 ")1 p.c. of all the species recorded for the plankton belong to the Des- 

 midiaceae. Nevertheless, though the English lakes contain so high a 

 percentage of species, they are not so rich in actual numbers of desmids 

 as the Scottish or Welsh lakes. Spondyhsium pulchrum var. planum is 

 abundant generally. A table shows the abundance of desmids in the 

 British lakes as compared with some of the lakes of continental Europe. 

 There are relatively few Protococcoideas, but the diatoms are very con- 

 spicuous in the plankton of some of the English lakes. The Myxo- 

 phyceas are almost as poorly represented as in the Scottish lakes, the 

 number of species being relatively few. Among the Flagellates, the 

 genus Binobryon is conspicuous ; and among the Peridinieae, Peridinium 

 WUUi. The latter is one of the leading features of the plankton of 

 the English lake district. Lists are given of those species which are 

 exclusively confined to the plankton, and of those which are much more 

 abundant in the plankton than elsewhere. The authors notice that 

 a greater bulk of plankton occurs in those lakes which are slightly 

 contaminated by the presence on their shores of small villages and farms, 

 and this they attribute to the slight increase of food constituents arising 

 from the sewage. The experience of the authors is not in support of 

 the view of Huitfeldt-Kaas, that small depth is favourable and great 

 depth unfavourable to the development of plankton. 



* Rhodora, xi. (1909) pp. 196-7. 



t Naturalist, Sept. 1909, pp. 323-31 (figs.). 



