452 NOTES AND MEMORANDA. 



able in many instances in the algal world, the authors adduce 

 the following considerations. 



In order to the formation of zoospores all the products of 

 assimilation collected in the chlorophyll-granules are in solu- 

 tion, and equably distributed in the protoplasm of the cell. 

 But in assimilation, which is in the most intimate dependence 

 with the light, an opposite process is set up. If, thus, a cell 

 be still capable of assimilation — if it be, so to say, still in a 

 vegetative state — it can arrive at zoospore formation only in 

 the night hours. But if, on the other hand, an organ be in 

 a resting state — if all the cell-substances be equably distri- 

 buted in the plasma — it then forms zoospores, after being 

 moistened with water, quite independently of the light at any 

 hour of the day or night. 



Touching the affinities of Botrydium, the authors regard 

 it as the type of a family (Botrydiacea?) of Isosporea?, equiva- 

 lent to Pandorineae and Hydrodictyese, with the following as 

 its characters : 



Isosporese presenting in germination a vegetative plant, 

 the contents of this becoming modified into an indefinite 

 number of resting-spores ; spore-contents, in germination, 

 becoming modified into a number of sexual zoospores, con- 

 jugating and forming isospores. 



Botrydium (Wallroth). 



Vegetative plants unicellular, increasing by cell-division 

 and zoospore-formation ; asexual zoospores uniciliate, sexual 

 biciliate; isospores sometimes globular, and alike capable of 

 germination, sometimes compressed and hexagonal, fur- 

 nished with a few tuberculate thickenings. 



B. gramilatum (L.), Grev. 



Vegetative plants elongated, with a hyaline end pene- 

 trating the soil, the opposite chlorophyll-containing end pro- 

 jecting into the air, inflated or sometimes subdividing, the 

 contents becoming modified during dryness into a number of 

 spores, becoming red ; these, on their part, giving rise to the 

 sexual zoospores, conjugating and furnished with two cilia. 

 Vegetative plants increasing also by cell-division and forma- 

 tion of asexual uniciliate zoospores, these germinating only 

 on moist earth, in water becoming surrounded by a double 

 membrane and passing into rest. Vegetative plants becoming 

 modified by increase of volume of their exposedinflated upper 

 portion, and simultaneous copious ramification of the subter- 

 ranean root into an almost globular, light green, ordinary 

 zoospovange, tapering off downwards, its contents under 



