230 SUMMARY OF CURRENT RESEARCHES RELATING TO 



enveloped in mucilage. The process corresponds in all essential points 

 to that already described in Fleodorina californica and P. illinoisensis. 

 The alga is frequently infested by the parasitic fungus Dangeardia 

 mamillata g. et sp. n.* 



Chlamydomonadinese. f — M. P. A. Dangeard gives an exhaustive 

 monograph of this family, — consisting of the genera Chlorogonium, 

 Gercidium, Lvbomonas g. n., Pltacotus, Ghlamydomonas, and Carter ia — 

 together with critical remarks on the structure, mode of reproduction, 

 and affinities of the lower Algae. Lobomonas Francei g. et sp. n. is a 

 lobed organism, somewhat resembling an amoeba with its pseudopodes ; 

 the zoospores pass into a state of repose, and then divide into 4 or 8 new 

 individuals ; no sexual mode of reproduction is known. 



The author regards the Uhlaniydomonadineae as forming one of the 

 lowest steps in the vegetable series, and marking a passage from the 

 Flagellates to the Chlorophytes. 



In the general portion of the paper the elements of the cell, the 

 division of the nucleus, and cell-reproduction, are discussed at length. 

 The disposition of the cytoplasm varies in the different species of Chlamy- 

 domonadineaa. It may be homogeneous or reticulated, and in both cases 

 either chromatic or achromatic. There is, in this group of Algse, a cyto- 

 plasmic network, the substance contained in the meshes being an inert 

 fluid. The cytoplasm may be chromatophilous or uncoloured. The 

 chromatiu-granules are especially fuchsinophilous. The flagella are 

 usually two in number, in Carteria there are four. Most species contain 

 one or more pyrenoids of a homogeneous substance ; they either multiply 

 by division or originate directly in the chloroplasm. Wherever the 

 presence of a nucleus has been demonstrated, it exhibits karyokinesis with 

 its complex phenomena. The nucleus consists of a nuclear membrane, one 

 or more nucleoles, and a nucleoplasm. Indirect division of the nucleus 

 (in contrast to karyokinesis) has been observed only in Chlorogonium. 

 A structure corresponding exactly to a ceutrosome was observed only 

 once (in Chlamydomonas monadina). Karyokinetic division goes through 

 its regular stages of prophasis and auaphasis. 



Just as, in the cytoplasm, there is a differentiation of elements with 

 definite functions, or, in a chlorophyllous cell, there are chloroleucites 

 which subserve a holophytic nutrition, so, in karyokinesis, there is a 

 differentiation from the protoplasm of bodies to which may be given the 

 name division-leucite or clasileucite. They often possess corpuscles 

 which are capable of multiplying by division or by new formation. 



The paper concludes with some general remarks and theories on 

 Sexual Reproduction. In the Chlamydoinonadineae the process consists of 

 the conjugation of two sexual zoospores or gametes formed in a gameto- 

 sporange ; the gametes may be naked or enclosed in a membrane ; the 

 conjugation may be isogamous or heterogamous ; and isogamy and hetero- 

 gamy may both occur in the same species. 



The author regards sexual reproduction as simply a modification of 

 primitive autophagy. Its object is to re-establish in the nucleus the 

 normal number of chromosomes which has, for the time, been reduced to 

 one-half by chromatic reduction ; this reduction is a necessary conse- 



* Cf. this Journal, 1899, p. 309. 



t Le Botaniste, vi. (1899) pp. 65-292 (20 figs.). 



