120 THE MICROSCOPE. [May, 



The Rhizopods are rarely visible to the naked eye, but they 

 abound everywhere if there is moisture or dampness — in ponds, 

 in lakes, in swamps, in sea, in ocean. Some grow in salt water 

 and some in fresh. Leidy has written only upon the fresh- water 

 forms. Ponds and ditches may be skimmed for specimens with 

 a small tin dipper, and the superficial ooze transferred to a bottle 

 to await examination. Often specimens may be scraped up from 

 wet ground with the blade of a knife, their presence being be- 

 trayed by the green algous material which is plainly visible. 

 Their pursuit is feasible at nearly all times of the year, even in 

 winter, if vegetation is not completely covered by ice and snow. 



At this time of year our readers may well begin the collection 

 of specimens, preserving them as described by Leidy and other 

 authorities. The Rhizopods are classified by Hitchcock (River- 

 side Natural History)in (i) Lobosa, (2) Radiolaria, (3) Helio- 

 zoa, (4) Reticularia. 



Of the Heliozoa, or sun animalcules, he says that they are very 

 beautiful, being mostly spherical and floating forms. A few are 

 attached by long pedestals. They put out delicate rays in all 

 directions from the centre, often exceeding the diameter of the 

 body in length. 



The most common of the Heliozoa is Actinophrys sol^ which 

 occurs in pools of standing water almost everywhere among float- 

 ing plants. Under a low power of the microscope it is a colorless, 

 spherical body,4-iooths to i3-iooths mm. in diameter. The great 

 number of delicate spines can be seen projecting from the body 

 to 3 or 4 times its diameter. But the most beautiful form of this 

 order is Clathruliiza elegans. Its capsules become yellow with 

 age, presenting a rich golden appearance, and it is often found 

 in ponds and ditches. 



A quite extended account of this Rhizopod was published in 

 The Ame?'ican Monthly Alicroscopical Jou7"nal for March, 

 1892. 



Common Forms of Fresh- Water Algae. 



By a. H. BRECKENFELD, 



SAN FRANCISCO, CAL. 



[Abstract of a paper read at the San Francisco Microscopical Society, March 2, 1892.] 



The Algae form one of the subdivisions of cryptogamous or 

 flowerless plants. They are all cellular, not vascular, and gen- 

 erally of a green color, though a few are brown or brownish-yel- 

 low. In point of structure the forms present considerable diver- 

 sity, some being unicellular, some filamentous or thread-like, and 

 some branching. While all are undoubtedly vegetable forms, 



