488 SUMMARY OF CURKENT RESEARCHES RELATING TO 



Thallophyta. 



Algae. 

 (By Mes. Ethel S. Gepp.) 



Colourless Rhizopodial Chrysomonad.* — A. Pascher found epiphytic 

 on OEdogonium grown under culture, a colourless rhizopodial Chryso- 

 monad of the type of Lagynion. He calls it Heterolaggaion CEdogoiui. 

 The principal points in connexion with it are as follows : The great 

 similarity of the shells between this colourless organism and the genus 

 of Chrysomonads ; the fact that Chrysomonads may throw out tem- 

 porary and also permanent rhizopodia ; that among the Flagellates as 

 well as among the rhizopodial forms of the Chrysomonads apochromatic 

 types appear ; that the present new organism produces leucosin, like 

 the other apochromatic and euchromatic Chrysomonads. The new find 

 is a proof of a closer relation between Rhizopods and Flagellates, and of 

 the erroneous position of many or all known Rhizopods. This also is 

 another indication that a "rhizopodial form" need not be at ail 

 characteristic of "primitive organization," but that the "rhizopodial 

 form" is only the morphological expression of a mostly secondary 

 adaptation to a certain mode of nutrition. 



Halosphsera.f — A. Pascher has made a study of material of 

 Halosphaera, collected in sixty-five localities in the Northern hemi- 

 sphere, and in seventeen in the Southern. The results^are as follows : 

 1. Halosphmm occurs in all oceans, without forming geographical 

 varieties. 2. Its northerly distribution is established up to 72° 45' N. 



3. The membrane consists of two portions closed together like a nut- 

 shell, composed principally of pectine, and containing also silica. 



4. During the growth of the cells new halves of the membrane are 

 formed inside the original ones, the old halves crack off like caps, and 

 remain sometimes adhering for a time to the cells. This is shown in 

 Gran's figures. 5. The numerous chromatophores, which not infre- 

 quently are connected together by differentiated bridges of protoplasm, 

 often contain a large quantity of carotin, and take a blue colour with 

 hydrochloric acid. The quantity of carotin varies greatly, 6. The 

 products of assimilation consist of fats and oils, never starch. There 

 occurs also in larger or smaller balls a brightly glittering body, the 

 chemical nature of which is unknown. 7. The nucleus, often eccentri- 

 cally placed, shows in division numerous chromosomes. Its chemical 

 composition varies from that of the ChlorophyceEe nucleus. 8. As 

 regards reproduction the following facts were established : (jx) The 

 formation of 8-128 globular 2-shelled aplanosphores, which set free 

 the mother-cells by a dehiscence of the shells ; {b) the formation of a 

 large resting-cell, which however does not fill up all the mother-cell ; 



* Ber. Deutsch. Bot. GeselL, xxx. (1912) pp. 152-8 (1 pi.). See also Bot. 

 Ceutralbl., cxxxii. (1916) p. 30. 



t Ber. Deutsch. Bot. GeselL, xxxiii. (1915) pp. 488-92. See also Bot. Centralbl, 

 cxxxii. (1916) pp. 31-2. 



