SPECIES IN THE DIATOMACE.E. 131 



The multiplication of synonyms may, however, be restrained 

 within moderate limits, if the scientific observer will exercise 

 due caution in the creation of new names, carefully abstaining 

 from designating the subjects of his study, until he has made 

 himself, as far as possible, acquainted with the labours of his 

 predecessors in the same field ; and until he has acquired, 

 from a wide examination of allied forms, in every stage and 

 condition of growth, sound and invariable rules, by which to 

 determine how far certain differences are to be regarded as 

 specific distinctions, or as accidental or transitional varia- 

 tions. 



In a branch of study to which many are attracted by the 

 excitement of novelty, and the laudable desire of discovery, 

 there is some danger that these important cautions may be 

 overlooked or neglected ; and if the student of larger experi- 

 ence can, by his remonstrance, curb the impetuosity of such 

 inquirers or impose upon them safe and certain rules of 

 observation and discrimination, so that the new science shall 

 not be burthened with an unnecessarily extended nomenclature, 

 he will be doing some good service, and saving future ob- 

 servers much painful and unprofitable labour. 



It is with this view that I venture to make a few remarks 

 upon the discrimination of species in the Diatomacese, a 

 department of nature now inviting and receiving much atten- 

 tion, and in which it is probable many real and presumed 

 discoveries, as regards new forms, will rapidly be made by 

 the host of observers who have been attracted to the study. 



Several years of close observation of these organisms have, 

 I believe, enabled me to clear up some of the more difficult 

 points in their structure and growth, and led me gradually to 

 the adoption of certain views, as to specific characters in their 

 regard, that it may be of some utility at the present moment, 

 and in anticipation of the contents of the second volume of 

 my Synopsis, to lay before the public. 



The ordinary Diatomaceous frustule seems to owe its 

 reproduction to the protoplasmic contents of the sporangial 

 frustule, formed by the process of conjugation. These spo- 

 rangia, like the seeds of higher plants, often remain for a long 

 period dormant, and are borne about by currents, or become 

 embedded in the mud of the waters in which they have been 

 produced, until the circumstances necessary to their develop- 

 ment concur to call them into activity. At such times their 

 silicious epiderms open to permit the escape of the contained 

 endochrome, which is resolved into a myriad of embryonic 

 frustules ; these either remain free, or surround themselves 

 with mucus, forming a pellicle, or stratum, and in a definite, 



K 2 



