0)1 a Dejwsit of Diatomacece at South Yarra. 159 



and the debris of echini, are ob\'ious to the unassisted vision ; 

 and by the aid of a common magnifier_, numerous foramini- 

 ferous shells are also readily apparent. In other specimens 

 these larger objects become more rare, and their place 

 appears to be supplied by an increased number of micro- 

 scropic forms of the Diatomaceoi, which are occasionally met 

 with in such infinite profusion as to give the semblance of 

 frosted silver to the eye, and to render, in a remarkable 

 degree, the mass in which they are contained specifically 

 lighter than water. In every piece of this mud which has 

 come under observation, these diatoms have been found in 

 greater or less abundance; and from inquiries that have been 

 instituted, it is estimated that the swamp has a depth of not 

 less than sixty feet ! How vast has been the extent of life 

 within this limited area, and how immeasurably the results of 

 actual examination of the exquisite beauty and delicate 

 tracing of these minute organisms transcend any ordinary 

 efforts of imagination to conceive, can only be appreciated by 

 the revelations of the microscope. 



The great improvements which have been effected during 

 the last few years in the achromatic microscope, the perfection 

 and precision to which it has attained as an instrument of the 

 highest value in the prosecution of scientific research, and 

 the increased and daily increasing numbers of those who resort 

 to its assistance in the pursuit of special branches of study, 

 or particular objects of inquiry, are rapidly enlarging the 

 boundaries of our knowledge in every portion of the world, 

 and in ever}- department of philosophical investigation. It 

 has been well remarked that he wlio sees Avith the naked eye 

 only sees but half that world Avhich God has made. Beyond 

 the limit of man's natural "sision the microscope has disclosed 

 another world Avhose first characteristic consists in the 

 minuteness of its organisms ; but in the study of those 

 apparently insignificant forms, have been solved some of the 

 highest problems in the history of organization. Hence, the 

 family of the Diatomacece has many points of peculiar interest. 

 Their presence in almost every running stream, in every 

 little pool of stagnant Avater, as Avell as in the loAvest depths 

 of the ocean, their use and application, as the severest tests of 

 the excellence and efficiency of our microscopic object-glasses 

 — the inconceivably delicate and minute markings of the 

 silicious coverings of many of their forms — the peculiarities 

 of their structure, development, and reproduction — and the 

 Avouderful oiliees Avliich they perform in the admirable eco- 



