4 MINUTE FORMS OF LIFE 



nificance, and, if a microscopist as well, is likely to be familiar 

 with the hosts of minute beings that people the same watery 

 world. 



A study of the microscopical forms of life in the lake 

 waters reveals in their forms and habits of life a vast signifi- 

 cance, corroborative of other evidences of the former condition 

 of the lakes as a sea. In pursuing the study of the minute 

 forms of life in the lake waters, the most convenient plan, and 

 that generally adopted, is to take samples from the water supply 

 by means of straining or filtering. How closely and accurately 

 the material thus obtained represents the conditions existing in 

 the great body of water is not easily ascertainable, and it is not 

 unlikely that some forms, and perhaps many of them, exist in 

 the waters of the lake that are not obtainable in the manner re- 

 ferred to. But, proceeding with the process of examination by 

 filtering, we find throughout the year vast quantities of the 

 forms of life common to fresh water, such as various species 

 of diatoms, desmids, protococcus*, oscillatoria, and other fami- 

 lies of confervoidca, and numerous entomostraca, infusoria, ro- 

 tatoria, rhizopoda, and other classes of protozoa. 



Among all these varied forms of teeming life with which 

 the lake water abounds, there are none, so far as I know, which 

 might not be expected to be found in fresh water, except among 

 the diatoms. But of the sixty odd species of diatoms which 

 are found in the filterings of o.ur water supply, there are at least 

 three, and perhaps more, which are representatives of marine 

 forms; these are the Rhizosolenia eriensis, Actinocyclus niagaras 

 and Amphiprora ornata, and to these should be added, in my 

 judgment, the Stephanodiscus niagarae. 



Of these forms the Rhizosolenia eriensis was first collected 

 by Mr. H. 0. G-aylord from the water supply of this city, and 

 was described and named by Professor H. L. Smith, of Geneva, 

 New York. This is the only species of Rhizosolenia yet found 

 in fresh water, all other species of the genus yet described being ma- 

 rine or fossil, and the recent forms mostly found in the stomachs 

 of salpae and ascidians. This diatom has so far only been found, 

 to my knowledge, in the waters of the lakes at Cleveland. Buffalo 

 and Chicago. The Amphiprora ornata, found in considerable num- 

 bers in the lake water at certain seasons, has also been reported 



