240 University of California Publications. [Botany 



Oscillatoria brevis Kiitzing. 

 Oscillatoria simplicissima Gomont. 

 Oscillatoria animalis Agardh. 

 Oscillatoria proboscidea Crouan. 

 Oscillatoria chalybea Mertens. 

 Oscillatoria sancta Kiitzing. 

 Oscillatoria limosa Agardh. 

 Oscillatoria tenuis Agardh. 

 Oscillatoria curviceps Agardh. 

 Oscillatoria splendida Greville. 

 Oscillatoria Bonnemaisonii Crouan. 

 Oscillatoria geminata Meneghini. 

 Oscillatoria amphibia Agardh. 

 Oscillatoria chlorina Kiitzing. 

 Oscillatoria laetevirens Crouan. 

 Oscillatoria acuminata Gomont. 

 Oscillatoria Oleni Agardh. 

 Phormidium wncinatum Gomont. 

 Phormidium favosum Gomont. 

 Phormidium submembranaceum Gomont. 

 Symploca Muscorum Gomont. 

 Spirulina subsalsa GSrsted. 

 Spirulina major Kiitzing. 

 Beggiatoa mirabilis Cohn. 

 Beggiatoa arachnoidea Rabenh. 



(&) COLLECTING AND PREPAEING MATERIAL. 



The habitat of these plants is such that it is difficult to avoid 

 getting sand and various kinds of debris along with almost every 

 collection. 



If microtome sections of these small plants are to be made, it 

 is exceedingly desirable to have clean material to cut ; and to ob- 

 tain this is quite troublesome, in some cases almost impossible. 

 This is particularly true of heterocysted forms like Nostoc, which 

 imprison sand within the gelatinous thallus. The writer was con- 

 fronted from the first with this difficulty, which necessitated the 

 invention of some methods whereby suitable material might be 

 procured. A few of these methods are given here. 



If Oscillatorias and other actively crawling forms which con- 

 tain sand and debris are to be used, the decantation method is 

 found to be simple and practical. The whole mass is put into a 

 tall jar and thoroughly shaken up, and then allowed to settle for 

 a short time, after which the lighter floating material containing 



