608 



RECORD OF CURRENT RESEARCHES RELATING TO 



diere, and will include the descrijition of a very large number of new 

 species. 



Algae from Lake Nyas?a.* — Dr. G. Dickie describes in a paper to 

 the Linnean Society some Algas collected 

 by Dr. Laws, of the Livingstonia Mission, 

 Lake Nyassa, East Africa, all the genera 

 of which are well-known European, &c., 

 forms. 



Of the Diatomaceae thirty-two species 

 are enumerated, nearly all of which are 

 also very widely diffused elsewhere ; the 

 exceptions are few, Diadesmis for in- 

 stance, hitherto confined to the West 

 Indies. 



The only peculiar form is Epithemia 

 clavata^ n. sp. : — " Mediocris, plus minusve 

 clavata, apicibus rotundato-obtusis, costis 

 validis subparallelis, 15 in • 001 ; latere 

 superiore (dorso) convexo, inferiore subrecto. 

 Long. = • 001 — • 007 poll." It was more 

 or less plentiful on aquatic Phgenogams, 

 but especially on Spirogyra. The clavate 

 form at once distinguishes it from any 

 known species ; at first sight it has a resem 

 blance to SiirireUa (see figures). The striae 

 projier are not represented here; they are 

 30 in -001. 



Epithemia clavata. 

 A, frontal ; B, lateral view 

 C, small frustule in outline 

 all " greatly ruagniflcd." 



Thallus of the Diatomacese.t — Mr. J. Deby differs from the 

 observations of Dr. Lanzi on this subject referred to in a paper by 

 Mr. Kitton, which will be found on p. 38. What Dr. Lanzi describes 

 as the " thallus," and as forming part of the living matter of the 

 diatom is, Mr. Deby points out, nothing beyond what has been hitherto 

 a matter of common observation, no species during a part at least of 

 its existence being without a thin protecting envelope resting directly 

 on the external surface of the siliceous envelope, and often so hyaline 

 that to see it it is necessary to employ chemical reagents. The 

 " thallus " is, in fact, nothing but an exudation, a special secretion. 



He also considers that the " spores " which Dr. Lanzi found 

 enveloped in the thallus are either granules of endochrome, drops of 

 oil, &c., or unicellular algae common in all stagnant waters, and which 

 are often met with enveloped in a mucous mass similar to that 

 described by Dr. Lanzi. 



Mr. Deby still further doubts the assertion of Dr. Lanzi as to his 

 having found a diatom in all its intermediate states from small spores 

 up to frustules arrived at complete matui-ity, and asks for additional 

 proofs of such assertions ; the proper proof he considers would be to 

 follow step by stej}, without discontinuing the observation, tlie exist- 



* ' Journ. Liun. See. (Bot.),' xvii. (1879) p. 281. 

 t ' Brebissonia," i. (1879) p. 113. 



