NOTES ON EECENT EESEARCH. 



1115 



J. B. Overton (Hull Bot. Lab. xxxv., Bot. Gaz. 1902, No. 33, pp. 363- 

 375, 2 plates) on the production of plants from non-fertilised seed, the 

 ovum developing precisely as if impregnated. Antennaria alpina and 

 species of Alchemilla are cited as other parthenogenetic examples. 



C. T. D. 



Plankton in the Thames. 



Phytoplankton of the Thames, Preliminary Report on. Algo- 

 logical Note. By F. E. Fritsch (Ann. Bot. vol. xvi., No. 63, p. 576).— The 

 free-swimming or floating plant-life of rivers has been very little studied, 

 and, as far as the author is aware, no paper on this subject has ever been 

 published in this country. This note, therefore, is of considerable 

 interest, and especially as it deals with an important river like the 

 Thames. It is worth note that marine species reach to about Kew, while 

 fresh-water species are there dying off. " The quantity of plankton- 

 organisms decreases steadily as we approach the river's mouth. Plankton- 

 hauls from the Thames at Kew showed that many of the Desmids and 

 Pediastrums are either dead or in a dying state, and many of the 

 Diatoms merely consist of the empty frustules. . . . Even at Kew a few 

 truly marine species (e.g. Coscinodiscus radiatus, Surirella ovata, 

 Rhaphoneis Rhombus) were found, and had my observations extended over 

 a greater length of time, more would probably have been discovered. I 

 do not think that many of the fresh-water forms found on the upper 

 reaches of the river will be met with much further down than Kew." 

 The collecting was done between Kew and Cookham on six separate days 

 during a period of little more than a month, and the examinations were 

 apparently made in the Jodrell Laboratory at Kew, whence the note is 

 dated. A table of fifty-six species of Chlorophycea, Conjugate, Bacil- 

 lariales, Schizophycecs, and Flagellatce is given, showing the distribution 

 and relative number of the species found. — R. I. L. 



Ovule Development. 



Piperaeeae, Development of. By D. S. Johnson (Bot. Gaz. xxxiv. 

 p. 321, No. 5 ; plates ix.-x.) — The author discusses the following struc- 

 tures of Piper sp. ; (i.) The ovule, seed, and fruit ; (ii.) The development 

 and germination of the seed of Heckeria ; (iii.) Germination of the seeds 

 of Peperomia and Heckeria ; (iv.) Summary and conclusions. A 

 peculiarity resides in the fact that the embryo- sac of Peperomia contains 

 16 free nuclei derived from the megaspore nucleus ; and that 8 are 

 fused to form the endosperm nucleus, 7 others are persistent near the 

 wall of the sac, and one near the egg in the position of a synergid. The 

 ripe seed has a very small endosperm, chiefly aleurone, but has an 

 abundant perisperm of starch. — G. H. 



Plant-Bkeeding. 



Plant-Breeding: Recent Work in New Jersey (U.S.A. Exp. 

 Stn. New Jersey, Report 1901). — Dr. B. D. Halstead gives some results 

 of experiments in plant-breeding carried out during last year. 



Lima Beans. — Crosses were obtained in the previous year between 



