646 SUMMARY OF CURRENT RESEA.R0HE8 RELATING TO 



this water might soften and swell the circumjacent cellulose, and 

 thus protuberances of the cellulose alone would easily arise. But if 

 instead of a mere exosmose of water through the wall, the growing 

 protoplasm be supposed to force a passage into the intercellular space, 

 a reasonable explanation is afforded of the origin of the tiny drops of 

 colourless protoplasm. Their position and form are strong proofs of 

 their origin in this way. Such buds arising as they would from the 

 colourless ectoplasm of the green cell, would necessarily be themselves 

 colourless. This hypothesis may be verified by direct observation. 



Thus we have two distinct modes of cell-formation simultane- 

 ously in progress — the ordinary vegetative process by transverse 

 fission and a process of gemmation. 



Fallacious Appearances in Fresh-water Algae.* — F. WoUe points 

 out that in Conferva floccosa and fiigacissima and Microspora vulgaris 

 the cell-contents frequently swell out into a globular form, the 

 envelope of the filament swelling up at the same time, thus presenting 

 a deceptive resemblance to similar conditions of Uhthrix and Hormo- 

 spora. Hormiscia moniliformis, Hormospora purpurea, and H. Hohhyi 

 exhibit a similar characteristic, and present each a close resemblance 

 to the fragmented condition of Conferva and TJlothrix that they might 

 readily be regarded as identical. Conferva punctalis has a condition 

 of this kind, which might correspond to a good species of Gloeotila. 



Absorptive Organs of Batrachospermum.t— M. Sirodot states 

 that it is a general law in the lower orders of vegetable life that 

 absorption is not effected by all the cells, but only by certain ones 

 provided for this purpose with very thin cell-walls. In the case of 

 resting reproductive cells the period of quiescence is marked by a 

 strong thickening of the cell-wall, the rupture of which inaugurates 

 a new period of activity. 



In the Batrachospermeffi the thickening of the cell-walls is 

 accompanied by anatomical changes. In the primary axes the trans- 

 verse cell- walls do not thicken equally over their whole surface ; in 

 the central point they retain their primitive character, or even dis- 

 appear, as is shown by the coagulation of the protoplasmic substance, 

 the protoplasmic contents of two contiguous cells becoming united by 

 a filiform connection which runs through the transverse wall. At the 

 same time that this communication is effected, the special organs of 

 absorption make their appearance, radical filaments growing from the 

 base of the thickened cells. The absorptive function of these filaments 

 is, however, temporary only; they ultimately become organs of 

 attachment. 



This structure has its simplest development in the non-sexual 

 form or Chantrausia ; in the sexual form or Batrachospermum it is 

 much more complicated. In normal circumstances the internodes 

 are partially or entirely covered by descending articulated fila- 

 ments, which continually increase in number, and which grow at first 

 from the basal cell of the fasciculated branches that constitute the 



* Amer. Mon. Micr. Journ., i. (1S80) pp. 21-2. 

 t Comptes Reudus, xcii. (1881) pp. 993-5. 



