100 SUMMAKY OF CURRENT RESEARCHES RELATING TO 



Cylindrocystis, and Microcystis must be regarded as probable synonyms 

 of Gloeocystis. 



Chromophyton Rosanoffii, * — Under this name M. Woronin 

 describes a very peculiar and interesting organism which he finds in 

 the form of a fine light yellow or brown dust on the surface of pools 

 in boggy districts in Finland. On warm, still, and sunny days the 

 surface of the water became completely covered with this dust, which 

 disappeared as soon as the weather became rainy. When removed 

 into a glass vessel, if the water is well shaken it becomes perfectly 

 clear ; but the surface is soon covered with the yellow coating if left 

 standing in a room. If sprinkled with water, it also disappears, as 

 under the influence of rain. It will remain, however, on the surface 

 of tbe water in the vessel through the autumn and winter, when it bas 

 completely disappeared in the open. 



If a drop of water covered with tbe yellow dust is carefully placed 

 on the slide so as not to moisten tbe dust, and without a cover-glass, 

 it is seen that the particles which compose it project above the surface 

 of the water in a variety of forms. The smallest are always 

 spherical, and from their sharp and usually very dark outline, appear 

 like little drops of oil or bubbles of air, but are distinguished from 

 the latter by a light yellow glistening. The larger particles are 

 spherical, hour-glass-shaped, moniliform, or vermiform ; and the largest 

 of all have extremely irregular forms. The larger particles appear 

 to consist of a colourless hyaline mucilaginous matrix, in which are 

 imbedded several irregular, rounded or ribbon-shaped, yellow bodies 

 having the appearance of flakes. The application of a higher power 

 shows these yellow particles to be so many zoospore-like bodies, each 

 of which is provided with a yellow pigment-spot. Occasionally they 

 have a slow power of motion within the matrix. 



That these bodies are true swarm-cells is at once shown by placing 

 a cover-glass on the dust. As soon as the particles become thus 

 immersed in the water, the colourless mucilaginous matrix swells up 

 violently, and the imbedded zoospores are set free, and at once begin 

 to move about actively. They are uniciliated, and consist of a colourless, 

 somewhat elongated, irregularly ellipsoidal protoplasm-body, which 

 is generally rounded at both ends, very rarely narrowed at the ends, 

 and has an average length of about 8-9 yu,, and breadth of 4-6 fx. 

 Much less often it is nearly spherical. At one side of the anterior 

 half of the zoospore is a yellow or bright yellow-brown pigment- 

 plate, apparently of similar composition to the diatomin of the Bacil- 

 lariacese. Heat or acetic or dilute sulphuric acid usually induces a 

 greenish colour in the dead zoospore. In the colourless protoplasmic 

 portion of the anterior half of the zoospore are several small granules 

 and one or two vacuoles, one of which is always contractile. The 

 colourless protoplasm of the posterior half is much more refractive, 

 and has more or less resemblance to a drop of oil. The cilium and its 

 point of attachment are revealed by treatment with iodine, which causes 

 the zoospore to become spherical with its cilium stretched out straight. 



* Bot. Ztg., xxxviii. (1880) pp. 625-31 and 641-8. 



