ZOOLOGY AND BOTANY, MICROSCOPY. ETC. 211 



cells are liberated by tbe rupture of the primary integument, and each 

 forms a new colony. At intervals a cell develops a spiny, cellulose coat 

 outside the integument, and becomes a resting-cyst. After a period of 

 quiescence it produces a new colony by simple cell-division, the remains 

 of the spiny coat being visible for a time. A colony of two cells with 

 integument measures about 55 /x x 45/*; a colony of four about 85/* x 

 GO//.. For mounting, it is recommended to place the material with 

 water at one end of a dish, which is covered over except at the opposite 

 end ; the organisms then leave the mud and travel towards the illu- 

 minated end, and can be removed with a pipette and preserved in the 

 following solution ; — Copper acetate 0*5 grm., distilled water 100 c.cm. ; 

 mix, and add at ordinary temperature gum acacia 65 grm. ; when it is 

 dissolved, add pure glycerin 55 c.cm., mercuric chloride 2 grm. ; filter 

 before use. 



Reproduction of Anabaena.* — F. E. Fritsch continues his studies 

 on the Cyanophyceas, and describes his researches on Anabcena Azollir. 

 He finds that the spore-contents in germination are either protruded 

 from the ruptured spore-membrane by the formation of mucilage, or 

 the spore-membrane itself becomes mucilaginous, while the contents 

 retain their original position in the thread. The gonidia are formed by 

 rejuvenescence, acquire a well-marked membrane, and are liberated by 

 one of two methods resembling those of spore-germination. The spores 

 have the power of germinating at once, while the gonidia pass through 

 a resting period after liberation'. 



Cyanophyceae.f — 0. P. Phillips publishes a comparative study of the 

 cytology and movements of the Gyanophyceae. He comes to the conclusi< m 

 that these plants are much higher in their organisation than has been 

 supposed, possessing, as they undoubtedly do, a chromatophore and true 

 nucleus. The nucleus undergoes part, at least, of the karyokinetio 

 process ; and the chromatophore is also primitive, combining the func- 

 tion of a colour-bearing organ with that of the cytoplasm. The cell 

 consists of a nucleus, a thin colourless ectoplasm, and between them a 

 thick band of pigmented cytoplasm — the chromatophore. In the 

 latter are located the cyanophycin-granules and slime-balls, which are 

 both probably food products. The nucleus divides by one of two 

 methods : either it stops short at the net-spireme stage and constricts 

 itself into halves ; or it continues further and forms a rudimentary 

 spindle with rudimentary chromosomes upon linin-tkreads. The move- 

 ments of Oscillaria, Cyliiulrospermum, etc., are explained by the presence 

 of delicate protoplasmic cilia, which radiate from the nucleus outwards 

 through pores in the cell-wall. .Similar protoplasmic processes occur on 

 the end cells of Oscillaria, etc. The protoplasts of the cells of fila- 

 mentous Cyanophyceaa are all connected by tine protoplasmic threads, 

 which pass through pores in the wall, especially a central pore. The 

 heterocyst is a modified vegetative cell packed with some substance, 

 perhaps modified chromatin. Spores arc formed in Oscillaria by the 

 fusion of two or more cells of the filament. The cell-wall is of 



* New Phytologist, Hi. (1904) pp. 216-2S (1 pi.). 



f Contr. But. Lab. Univ. Pennsylvania, ii. (ls»04) pp. 237-835 (3 pla.). 



