160 On a Deposit of Diatonmceae at South Ym'ra. 



iiomy of infinite wisdom and intelligence^ as " the invisible 

 scavengers of nature/^ have made them the subjects of de- 

 lightful and instructive study^ wherever the means of their 

 examination by the microscope have extended. ^'^ As a group 

 of simple organisms they present us with the first struggles 

 of life against the physical and chemical forces of mere matter; 

 and it is by the observation and determination of these 

 elementary forms that we are enabled to proceed^ in the spirit 

 of true philosoph}^^ to the accurate investigation of higher 

 forms of structure ; and thus the theory of cell-formation^ as 

 carefully elaborated under the scrutiny of the microscope, 

 has become the foundation of all our certain knowledge of 

 vegetable organization." 



These objects^ then^ so apparently trivial to ordinary ob- 

 servers, possess a degree of interest, actual and relative,, which 

 is far beyond their nominal position in the scale of scientific 

 arrangement. In the present state of our nomenclature, the 

 family of the Diatoinacece occupies a kind of anomalous situa- 

 tion between the animal and vegetable kingdoms, in exhibit- 

 ing certain characteristics of both. Ehrenberg and some 

 other microscopists have placed them among the lowest forms 

 of animal life ; while the late Professor AYilliam Smith, in 

 his laborious monograph of the British Diatomacese, Professor 

 Carpenter, and a host of other celebrated observers, have un- 

 hesitatingly described them as belonging to the vegetable 

 kingdom. The preponderance of opinion undoubtedly inclines 

 to their vegetable nature, notAvithstanding the power of inde- 

 pendent locomotion, and the presence of ciliary actions^ 

 which some species have been ascertained to exhibit. What- 

 ever doubt may exist on this subject, appears to arise from 

 the difficulty of reconciling the movements which accompany 

 the vital functions of the Diatomacece with the prevalent 

 conditions of plant life, and of harmonizing their silicious 

 epiderms with the ordinary forms under which cellulose 

 occurs throughout the vegetable kingdom. On the other handj 

 it will be remembered that most decided movements are pre- 

 sent in the OscUlatorioi , and that silica is ever constant in the 

 structui'e of the epiderm of the Equisitacece and the Grami- 

 nacece. An enlarged consideration of these and other facts, 

 therefore, conduces to the view that the Diatomacece, with 

 specialities of their own, have intimate alliances with the 

 other orders of Unicellular Algas, and belong to the vegetable, 

 rather than the animal kingdom. 



The forms which these objects present in a living state 



